Dissertations / Theses on the topic 'Rockfalls'

The present thesis aims at the analysis of the fragmentation of rockfalls. The fragmentation is a complex phenomenon poorly understood with a lack of tools to reproduce it on rockfall simulators. The effect of fragmentation on the hazard assessment and mapping is significant and it may substantially modify the risk scenario. The analysis of the empirical data acquired in a series of inventoried natural rockfalls and real-scale drop tests, clearly suggests that fragmentation displays a fractal behavior. Based on these observations, a fractal fragmentation model is proposed heare, adapting the basics of Perfect (1997) to the specific case of rockfalls. An important development of the thesis presented is the procedure to characterize the rockfall mass before and after the fragmentation, which include the methodology to measure the block size distributions of the deposit, the use of Unmaned Aerial Vehicles (UAV) equipped with digital camera digital, and the photogrammetric analysis to reconstruct the detached block volumes based on 3D models and discrete joint characterization. The block size distributions before and after the fragmentation are related with the proposed model, using the real data to calibrate the model parameters by back analysis. The methodologies and the model proposed contribute to the understanding of the fragmentation phenomenon and have the capability to reproduce the entire block size distribution and the calculation of the number and volume of the fragments. They also allow the quantification of the areas of the fresh faces created due to breakage, which may be related to the required fragmentation energy. The final goal of the ongoing research is the implementation of fragmentation behavior on a rockfall simulator which is currently under developed within the Rockmodels project (https://rockmodels.upc.edu/es), and modify the criteria to calculate the probability of impact used in hazard mapping and in quantitative risk assessment studies. The results of the fragmentation model may also contribute to the analysis of the efficiency and to the design of the rockfall protection systems.
La present tesis es centra en el fenomen de la fragmentació en despreniments rocosos. La fragmentació és un fenomen complex de difícil caracterització i de la que ens manquen eines per a la seva modelació en programes de simulació de caiguda de blocs. Tanmateix, els efectes de la fragmentació sobre les prediccions i els conseqüents mapes de perill poden comportar modificacions en l’escenari de risc. A partir d’un conjunt de dades empíriques obtingudes mitjançant l’inventari de despreniments naturals, s’ha observat un clar comportament fractal. A partir d‘aquestes observacions, s’ha proposat un model de fragmentació fractal adaptant la descripció de Perfect (1997) al cas específic del despreniment rocós. Una part important del desenvolupament de la tesi són les metodologies utilitzades per a la caracterització de la massa rocosa abans i després de la fragmentació, des de metodologia per mesurar distribucions de volums de blocs al dipòsit, fins a la utilització de drons i fotogrametria digital per reconstruir el volums dels blocs abans de caure a partir de models 3D i de la caracterització discreta de les discontinuïtats del massís. Les distribucions de volums de blocs abans i després de la fragmentació és relaciones mitjançant el model de fragmentació proposat, utilitzant les dades reals per calibrar els paràmetres del model per retro anàlisis. La utilització de les metodologies proposades i del model de fragmentació ajuden a la comprensió del fenomen, permeten la reproducció de la distribució de blocs sencera amb una estimació del nombre de blocs i el seus volums. També permet una quantificació de la superfície nova creada en cares fresques degut a la ruptura, que es vincula amb l’energia dedicada a la fragmentació. L’objectiu final d’aquesta recerca és la implementació de la fragmentació en un simulador de caiguda de blocs que es troba en desenvolupament en el marc del projecte Rockmodels (https://rockmodels.upc.edu), així com modificar els criteris de càlcul de probabilitat d’arribada que s’utilitzen per elaborar els mapes de perill i els estudis quantitatius del risc. Les conclusions poden canviar la manera com es dissenyen els sistemes de protecció contra despreniments.
La presente tesis se centra en el fenómeno de la fragmentación en desprendimientos rocosos. La fragmentación es un fenómeno complejo de difícil caracterización y de la que nos faltan herramientas para su modelación en programas de simulación de caída de bloques. Sin embargo, los efectos de la fragmentación sobre las predicciones y los consecuentes mapas de peligro pueden conllevar modificaciones en el escenario de riesgo. A partir de un conjunto de datos empíricos obtenidos mediante el inventario de desprendimientos naturales, se ha observado un claro comportamiento fractal. A partir de estas observaciones, se ha propuesto un modelo de fragmentación fractal adaptando la descripción de Perfect (1997) en el caso específico del desprendimiento rocoso. Una parte importante del desarrollo de la tesis son las metodologías utilizadas para la caracterización de la masa rocosa antes y después de la fragmentación, desde metodología para medir distribuciones de volúmenes de bloques en el depósito, hasta la utilización de drones y fotogrametría digital para reconstruir el volúmenes de los bloques antes de caer a partir de modelos 3D y de la caracterización discreta de las discontinuidades del macizo. Las distribuciones de volúmenes de bloques antes y después de la fragmentación se relacionan mediante el modelo de fragmentación propuesto, utilizando los datos reales para calibrar los parámetros del modelo mediante retro análisis. La utilización de las metodologías propuestas y del modelo de fragmentación ayudan a la comprensión del fenómeno, permiten la reproducción de la distribución de bloques entera con una estimación del número de bloques y sus volúmenes. También permite una cuantificación de la superficie nueva creada en caras frescas debido a la ruptura, que se vincula con la energía dedicada a la fragmentación. El objetivo final de esta investigación es la implementación de la fragmentación en un simulador de caída de bloques que se encuentra en desarrollo en el marco del proyecto Rockmodels (https://rockmodels.upc.edu), así como modificar los criterios de cálculo de probabilidad de alcance que se utilizan para elaborar los mapas de peligro y los estudios cuantitativos del riesgo. Las conclusiones pueden cambiar la forma en que se diseñan los sistemas de protección contra desprendimientos.

The fragmentation process in rockfalls is a complex phenomenon that is not well understood and only a few rockfall simulation models consider it explicitly. Fragmentation significantly affects the evaluation of the hazard and therefore of the risk. This thesis aims to develop a rockfall propagation model that is capable of reproducing the fragmentation phenomenon in rockfalls and to assess its consequences in the risk analysis. Four real-scale tests in a quarry and one laboratory test were performed for a better understanding of the fragmentation process. During these tests, several remote sensing techniques were used to capture the motion of the blocks and the fragment size distributions of the resulting deposit. The analysis of the empirical data acquired confirmed that the mass distribution produced by the fragmentation of a single block can be adequately described using fractal theory. Moreover, it was observed that the envelope of the trajectories of the newly generated fragments adopted the shape of a cone. The knowledge gathered with these experiments led to the development of RockGIS, a stochastic program based on a lumped mass approach for the numerical simulation of rockfalls and their fragmentation using a fractal model. The model simulates the trajectories of the blocks using state-of-the-art methodologies and implements an innovative fragmentation module to consider block breakage using fractal theory. The code was developed within the framework of the Rockmodels project (https://rockmodels.upc.edu). In the simulation, the parameters that define the sizes of the fragments generated are computed at each impact according to the kinematic conditions. This approach allows different fragmentation patterns to be reproduced depending on the energy conditions of the impacts. The performance of the RockGIS code was verified and validated by the real-scale rockfall tests carried out and by reconstructing three inventoried natural rockfall events that took place in Spain: a 10,000 m³ rockfall near Vilanova de Banat (Eastern Pyrenees) in 2011, a 800 m³ rockfall in Monasterio de Piedra in 2017 (Zaragoza) and a 10 m³ rockfall on the Ma-10 road (Mallorca). For the calibration of the model different goodness-of-fit indicators were considered depending on the information available in each case study. Two main calibration criteria were used: the runout distance and the size distributions of all the fragments generated. Moreover, the fragment scattering along the slope, the number of blocks crossing a reference line, the position of the center of gravity of the whole deposit and other criteria were used in some scenarios to validate the simulation results. The parametric analysis showed that the model is highly sensitive to the parameters that control the fragmentation process. The performance of the fragmentation model developed is satisfactory and accomplishes the goal of representing the fragmentation process, as it is able to reproduce the field observations accurately. To use this approach for risk analysis and the design of protective measures, precise calibration is required to ensure the parameters are appropriate for each case study considered. Regarding the risk analysis, fragmentation has both a significant and a contrasting effect on the risk value and should not be ignored. The most significant effect is on the rockfall runout distance. Fragmentation may significantly reduce rockfall propagation if the slope is sufficiently gentle and long. In this case, the new fragments generated mobilize less energy and can be trapped by the topographic irregularities, obstacles and protection works. Conversely, a wide range of block sizes are able to reach corridors running below steep slopes. In such a situation, fragmentation facilitates the divergence of the blocks’ trajectories, which increases the probability of impact on people and vehicles and consequently the risk.
La fragmentació en despreniments rocosos és un fenomen complex, poc comprès i només alguns models de simulació de caigudes de roques la consideren explícitament. La fragmentació afecta l’avaluació del perill i conseqüentment l’avaluació del risc. L’objectiu d’aquesta tesi és desenvolupar un model de propagació de despreniments rocosos capaç de reproduir la fragmentació i avaluar les conseqüències de considerar-la en l'anàlisi del risc. Per millorar la comprensió del fenomen, s’han realitzat quatre assajos a escala real i un assaig al laboratori. L'anàlisi de les dades experimentals adquirides confirma que la distribució de volums produïda per un procés de fragmentació d'un bloc es pot descriure adequadament mitjançant la teoria del fractal. A més, han permès confirmar la hipòtesi que les trajectòries dels fragments que resulten de la fragmentació d’un bloc es mantenen dins d’un límit en forma de con. El coneixement recollit en aquestes campanyes experimentals ha permès el desenvolupament de RockGIS, un programa estocàstic basat en una aproximació puntual de la massa per a la simulació numèrica de despreniments rocosos i la fragmentació mitjançant un model fractal. El model simula les trajectòries dels blocs basant-se en les metodologies més recents i implementa un mòdul de fragmentació innovador que contempla la ruptura dels blocs gràcies a un model de fragmentació fractal desenvolupat en el marc del projecte Rockmodels (https://rockmodels.upc.edu). Segons les condicions cinemàtiques, a cada impacte es calculen els paràmetres del model de fragmentació que defineixen els volums dels nous fragments. Aquest enfocament permet reproduir diferents escenaris de fraccionament en funció de les condicions energètiques dels impactes. El funcionament del codi RockGIS ha estat verificat i validat per mitjà d’assajos a escala real i segons tres despreniments rocosos naturals inventariats que han tingut lloc a Espanya: un despreniment de 10.000 m³ a prop del poble de Vilanova de Banat (Pirineus orientals) el 2011, una caiguda de 800 m³ a Monasterio de Piedra el 2017 (Saragossa) i una caiguda de roca de 10 m³ a la carretera Ma-10 (Mallorca). Per calibrar el model es van considerar diferents indicadors de bondat d’ajust segons les dades disponibles en cada cas d’estudi. Es van utilitzar dos criteris principals de calibratge: l’abast, o distància recorreguda, dels fragments generats i la distribució de volums. A més, en alguns dels escenaris estudiats es van considerar criteris addicionals de calibratge com ara la dispersió lateral dels fragments al llarg del vessant, el nombre de fragments que traspassaven una línia de referència, la posició del centre de gravetat de tot el dipòsit, etc. Els resultats del model desenvolupat són satisfactoris i compleixen amb l’objectiu de representar la fragmentació en els despreniments rocosos, ja que és capaç de reproduir les observacions de camp de manera precisa. Per emprar la metodologia proposada en l’estimació del risc i el disseny de mesures de protecció, cal un calibratge precís per tal de garantir que els paràmetres seran adequats a cada cas d'estudi considerat. Pel que fa a l’anàlisi del risc, la fragmentació té un efecte significatiu i contrastat sobre el valor del risc i no s’ha d’ignorar. Principalment afecta al càlcul de l’abast màxim dels blocs. La fragmentació pot reduir significativament la propagació dels despreniments si el pendent és prou suau i llarg. En aquest cas, els nous fragments generats mobilitzen menys energia i poden quedar atrapats per les irregularitats topogràfiques, els obstacles i les obres de protecció. Per contra, una àmplia gamma de mides de blocs poden arribar als elements exposats que es troben sota de vessants amb inclinacions altes. En aquests casos, la fragmentació facilita la divergència de les trajectòries de blocs, cosa que augmenta la probabilitat d’impacte amb els elements exposats i el risc consegüent
La fragmentación en desprendimientos rocosos es un fenómeno complejo, poco comprendido y sólo algunos modelos de simulación de caídas de rocas la consideran explícitamente. La fragmentación afecta la evaluación del peligro, y consecuentemente la evaluación del riesgo. El objetivo de la presente tesis es desarrollar un modelo de propagación de desprendimientos rocosos capaz de reproducir la fragmentación y evaluar las consecuencias de considerarla en el análisis del riesgo. Para mejorar la comprensión del fenómeno, se realizaron cuatro ensayos a escala real y un ensayo en el laboratorio. El análisis de los datos experimentales adquiridas confirma que la distribución de volúmenes producida por un proceso de fragmentación de un bloque se puede describir adecuadamente mediante la teoría del fractal. Además, han permitido confirmar la hipótesis de que las trayectorias de los fragmentos resultantes de la fragmentación de un bloque se mantienen dentro de un límite en forma de cono. El conocimiento recogido en estas campañas experimentales ha permitido el desarrollo de Rock-GIS, un programa estocástico basado en una aproximación puntual de la masa para la simulación numérica de desprendimientos rocosos y su fragmentación mediante un modelo fractal. El modelo simula las trayectorias de los bloques basándose en las metodologías más recientes e implementa un módulo de fragmentación innovador que contempla la ruptura de los bloques gracias a un modelo de fragmentación fractal desarrollado en el marco del proyecto Rockmodels (https://rockmodels.upc.edu). Los parámetros del modelo de fragmentación que definen los volúmenes de los fragmentos generados utilizados en la simulación, se calculan en cada impacto según las condiciones cinemáticas. Este enfoque permite reproducir diferentes escenarios de fragmentación en función de las condiciones energéticas de los impactos. El funcionamiento del código RockGIS ha sido verificado y validado mediante ensayos a escala real y según tres desprendimientos rocosos naturales inventariados que han tenido lugar en España: uno de 10.000 m3 cerca de Vilanova de Banat (Pirineos orientales) el 2011, uno de 800 m3 en Monasterio de Piedra en 2017 (Zaragoza) y uno de 10 m3 en la carretera Ma-10(Mallorca). Para calibrar el modelo se consideraron diferentes indicadores de bondad de ajuste según los datos disponibles en cada caso de estudio. Se utilizaron dos criterios principales de calibración: el alcance, o distancia recorrida, de los fragmentos generados y su distribución de volúmenes. Además, en algunos casos se usaron criterios adicionales de calibración como la dispersión lateral de los fragmentos a lo largo de la vertiente, el número de fragmentos que traspasaban una línea de referencia, la posición del centro de gravedad de todo el depósito etc. Los resultados del modelo desarrollado son satisfactorios y cumplen con el objetivo de representar la fragmentación en los desprendimientos rocosos, ya que es capaz de reproducir las observaciones de campo de manera precisa. Para emplear la metodología propuesta en la estimación del riesgo y el diseño de medidas de protección, se requiere una calibración precisa para garantizar que los parámetros son adecuados a cada caso de estudio considerado. En cuanto al análisis del riesgo, la fragmentación tiene un efecto significativo y contrastado sobre el valor del riesgo y no se debe obviar. Principalmente afecta al cálculo del alcance máximo de los bloques. La fragmentación puede reducir significativamente la propagación de los desprendimientos si la pendiente es bastante suave y largo. En este caso, los nuevos fragmentos generados movilizan menos energía y pueden quedar atrapados por las irregularidades topográficas, los obstáculos y las obras de protección. Por el contrario, una amplia gama de tamaños de bloques puede llegar a los elementos expuestos que se encuentran debajo de laderas con inclinaciones altas. En estos casos, la fragmentación facilita la divergencia de las trayectorias de bloques, aumentando así la probabilidad de impacto con los elementos expuestos y el consecuente riesgo.

Rockfalls is a major problem around the world, if they occur in populated areas, they can cause major damage to infrastructure, injure or kill people. For this reason, it is important to be able to predict where the risk of rockfalls and how to prevent and protect populated areas from them. However, it is no easy task to predict rockfalls. Although if an area with potential area for rockfall is localized it may seem easy to construct protective meshing or bolting potential blocks down. But in many cases this is not easy to do due to practical issues or economic reasons, for example in rock cuts on older railways in Sweden. Fall heights from rock cuts like that are not particularly high but the risk of damage to the trains and infrastructure in the track area is high, however, it is unknown how extensive the damage may be. Trafikverket, the Swedish authority responsible for Sweden's roads and railways, has for some years investigated a new method for classifying and minimize the risk of rockfalls from rock cuts next to the railways. This study include aims to include the potential maximum distance of a block from the rockfall can travel to the existing method. This master's work is part of the investigation and will include full scale field test where the rockfalls are examined by filming them and then evaluate the “bounce coefficient”, coefficient of restitution, from the individual rockfalls using photogrammetric methods. During the field study, a geotechnical testing equipment, DCP test rig, to be evaluated for its ability of an easy way in the field to produce an estimated value on the coefficient of restitution. During the evaluation, two rockfall simulating software be used to investigate how well the results from them match the true blocks movements.
Stenras är ett stort problem runtom i världen, om de inträffar i bebyggda områden kan de leda till stora skador på infrastruktur, skador eller dödsfall. Av den anledningen är det viktigt att kunna förutse vart det finns risk för stenras och hur man kan förebygga dem och skydda bebyggda områden från dem. Dock är det ingen lätt uppgift att förutse stenras. Även om det finns ett potentiellt område för stenras kan det tyckas lätt att placera ut skyddsnät eller bulta fast potentiella block. Men i många fall är detta inte praktiskt, eller ekonomiskt, till exempel i bergsskärningar på äldre järnvägar i Sverige. Fallhöjderna här är inte speciellt höga men risken för skador på tåg och infrastruktur i spårområdet är hög, dock är det okänt hur omfattande skadorna kan bli. Trafikverket, den svenska myndigheten som ansvarar för Sveriges vägar och järnvägar, har under flera år utrett en ny metod för att klassificera och minimera riskerna för stenras från bergskärningar bredvid järnvägar. Denna utredning syftar bland annat till att till att väga in det potentiella maximalt avstånd ett block från stenras kan färdas i den befintliga modellen. Det här mastersarbetet är en del i den utredningen och kommer att innefatta ett fullskaligt fältförsök där stenras undersöks genom att de filmas och sedan utvärderas studskoefficienten, coefficient of restitution, från de enskilda rasen i stereo. Under fältstudien kommer en geoteknisk testutrustning, DCP test rigg, att utvärderas för sin förmåga att lätt i fält få fram ett uppskattat värde på studskoefficienten. Under utvärderingen kommer två stenrassimuleringsprogram att användas för att undersöka hur väl de stämmer med de verkliga blockens rörelser.

Railway operators mitigate the risk of derailments caused by hazardous rocks falling onto the track by installing slide detector fences (SDF). These consist of electrical sensing wires strung on poles located uphill of the track; falling rocks snap these wires and trigger an alarm. Rocks of non-threatening size and migrating animals frequently break the wires causing prolonged false alarms and delaying rail traffic until the SDF is manually repaired, often in a hazardous environment. This thesis is concerned with the development of a prototype of the autonomous Seismic Rockfall Detection System (SRFDS) as a potential replacement for the SDF. Analysis and classification of natural and anthropogenic seismic signals which have been observed at the SRFDS field installations, is presented. A method for identification of hazardous rocks (>0.028 m³) using an empirical peak ground velocity attenuation model is outlined. Pattern recognition techniques which are based on cross-correlation and on variations in the short-term / long term averages of the ground vibrations are introduced for rail traffic identification and rockfall detection. The techniques allow the SRFDS to eliminate false activations by rail traffic, report hazardous rocks with minimum (< 3 s) delay, and rearm automatically when a false alarm is revealed. Performance of the SRFDS field installations was modeled using continuous seismic data recorded at two locations where the SRFDS and the SDF operate in parallel. The SRFDS computer model detected all major rock slides; it was significantly less likely than the SDF to be triggered by animal migration, but may be susceptible to thermal noise in very specific situations. A comparison of the actual number of the train delays caused by the existing SDF with those of the SRFDS computer model, shows that the use of the SRFDS will reduce the average number of delayed trains. The actual reduction of the number of delayed trains is between 3 and 8 times, depending on the location. Train delays caused by false triggers induced by construction activities and track maintenance could still exist; however, they can be eliminated by the adoption of the appropriate track management procedures.
Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate

Les risques d'éboulements doivent être évalués et surveillés afin de prévenir les pertes de vies humaines et dommages aux infrastructures. A cet égard, il est important de créer des catalogues d'événements et de comprendre la dynamique des éboulements. Les ondes sismiques peuvent être utiles à cette fin, car elles transmettent des informations précieuses sur l'événement. Elles sont générées lorsque des éboulements touchent le sol et peuvent être utilisées pour détecter, classer et localiser des événements. Plus encore, on peut déduire des propriétés des éboulements telles que leur volumes et leur comportement dynamique. Cependant, les signaux sismiques hautes fréquences (>1Hz) sont mal compris. En effet, ils sont associés à des sources sismiques complexes qui sont réparties dans l'espace et peuvent varier rapidement dans le temps. De plus, les ondes sismiques hautes fréquences sont susceptibles d'être diffusées et diffractées en raison des interactions avec les hétérogénéités du sol ou la topographie de surface. Cette thèse franchit une étape importante dans la compréhension des signaux sismiques hautes fré-quences des éboulements en simulant la propagation des ondes sismiques en utilisant la méthode des éléments spectraux (SEM) avec des profils de vitesse réalistes et des topographies de surface 3D. L'influence de la topographie sur le champ des ondes sismiques est étudiée. On constate que l'ampli-fication induite par la topographie est sensiblement différente entre les sources situées en profondeurs et celles situées en surface. En effet, les ondes de surface générées par des sources peu profondes sont exposées à une diffusion et à une diffraction constantes lorsqu'elles se déplacent le long de la surface. La désintégration de l'énergie le long de la surface est étudiée pour différents modèles de vitesse et des équations sont dérivées pour calculer rétroactivement l'énergie sismique totale rayonnée par la source. Ceci est intéressant du fait du lien entre l'énergie sismique et le volume d'éboulement. Afin de tenir compte des effets topographiques, il est proposé un facteur de correction qui peut être introduit dans le calcul de l'énergie. Les signaux sismiques générés par les éboulements du cratère Dolomieu du Piton de la Fournaise, à La Réunion, sont analysés. Les sismogrammes synthétiques sont utilisés pour identifier et interpréter les signaux observés qui sont générés par des impacts uniques. L'influence de la topographie sur les formes d'onde est démontrée et la sensibilité avec l'emplacement et la direction de la source est évaluée. Les caractéristiques du signal telles que les amplitudes et le contenu fréquentiel sont expliquées sur la base de la théorie du contact de Hertz. De plus, les rapports spectraux entre stations, calculés à partir des signaux sismiques d'éboulement, sont considérés comme caractéristiques de la position de la source. La comparaison avec les rapports spectraux simulés suggère qu'ils sont dominés par la propagation le long de la topographie plutôt que par le mécanisme de la source. Sur la base de ces résultats, une méthode est proposée pour la localisation des éboulements à l'aide de rapports énergétiques simulés entre stations. La méthode est appliquée pour localiser les éboulements dans le cratère de Dolomieu. La mise en œuvre de la méthode implique une fenêtre temporelle glissante qui permet une application simple sur des signaux sismiques continus. L'accent est mis sur la capacité de la méthode à surveiller l'activité des éboulements en temps réel
Rockfall hazard has to be evaluated and monitored in order to prevent loss of life and infrastructure. In this regard it is important to create event catalogs and understand rockfall dynamics. Seismic waves can help for this purpose as they carry valuable information of the event. They are generated when rockfalls impact the ground and can be used to detect, classify and locate events. Beyond that, rockfall properties such as their volume and their dynamic behavior can be inferred. Yet, high frequency seismic signals (>1Hz) are poorly understood. This is because they are associated to complex seismic sources which are spatially distributed and can rapidly vary over time. On top of this, high frequency seismic waves are prone to be scattered and diffracted due to interactions with soil heterogeneities or surface topography. This thesis takes an important step forward to enhance understanding of high frequency rockfall seismic signals by simulating seismic wave propagation on domains with realistic velocity profiles and 3D surface topographies using the Spectral Element Method (SEM). The influence of the topography on the seismic wave field is investigated. It is found that topography induced amplification is substantially different between deep sources and sources located at the surface. This is because surface waves generated by shallow sources are exposed to constant scattering and diffraction when traveling along the surface. The energy decay along the surface is investigated for different velocity models and equations are derived to back-calculate the total seismic energy radiated by the source. This is of interest as the rockfall seismic energy is related to the rockfall volume. In order to account for topography effects, a correction factor is proposed which can be introduced in the energy calculation. Observed seismic signals generated by rockfall at Dolomieu crater on Piton de la Fournaise volcano, La Réunion, are analyzed. Synthetic seismograms are used to identify and interpret observed signals generated by single impacts. The influence of topography on the waveforms is demonstrated and the sensitivity on source location as well as source direction is evaluated. Signal characteristics such as amplitudes and frequency content are explained based on Hertz contact theory. Additionally, inter-station spectral ratios computed from rockfall seismic signals are shown to be characteristic of the source position. Comparison with simulated spectral ratios suggest that they are dominated by the propagation along the topography rather than the mechanism of the source. Based on these findings, a method is proposed for the localization of rockfalls using simulated inter-station energy ratios. The method is applied to localize rockfalls at Dolomieu crater. The implementation of the method involves a sliding time window which allows a straightforward application on continuous seismic signals. The potential of the method to monitor rockfall activity in real-time is emphasized

Due to the exponential grown of the population within the last decades, the landslide hazard assessment of earthflows and rockfalls and their hazard mapping have become an essential tool for the territory management, mostly in mountainous areas. The landslide hazard was defined as the probability of occurrence of a potentially damaging phenomenon in a certain area and within a given period of time. Thus, the probability of occurrence (or frequency) for each type of landslide and magnitude must be known. The aim of this research is to develop an objective, quantitative and reproducible methodology to obtain the magnitude-frequency relations for medium and large size earthflows and rockfalls. This procedure has been set up in the Barcedana Valley and Montsec Range for large earthflows and rockfalls, respectively. Both study areas are located within the Tremp Basin (Eastern Pyrenees). Concerning the earthflows, they have been split between 1) reactivations and 2) intact slopes. The frequency of the reactivations has been obtained by analysing 11 sets of orthophotos covering a period from 1956 to 2013. The magnitude has been calculated as the area of the landslides obtained from the landslide mapping and from the orthophotos. The resulting magnitude-frequency relation for reactivations has been used to derive the probability of landslide reactivation for a given volume. It has been compared with probability of landslide reactivation obtained from the rainfall threshold responsible for the reactivation of 4-large landslides located within the Tremp Basin as well. The reactivation date has been estimated by means of dendrogeomorphology and the rainfall threshold has been determined by means of ROC analysis. The susceptibility of first-time slope failures have been obtained using a deterministic model named SINMAP. The frequency for each susceptibility class has been calculated using the inventory of first-time failures identified in the field and by means of orthophotos. An algorithm to obtain the area of the earthflows larger than the pixel size has been developed through an automatic aggregation of pixels located within the same slope and having the same susceptibility class. The obtained magnitude-frequency relation of first-time failures has been compared with the one obtained from the mapped first-time failures. Finally, the magnitude-frequency matrix for hazard mapping of intact slopes has been defined. Concerning the rockfalls, a methodology to obtain the rockfall scar size distribution of a cliff has been defined. It has been assumed the rockfall scar volumes as proxy for the rockfall volumes. In that case, the distribution of rockfall scars has been calculated using a high resolution point cloud of the rockwall obtained by a terrestrial laser scanner and following. Several volume distributions have been calculated to take into account the different detachment mechanisms and the consequent range of detached volumes. Finally, a procedure has been developed to convert form statistical frequency (% of scar volumes), calculated in the previous step, to temporal frequency (annual number of the scar volumes). To this, the total volume of material lost has been computed using the afore-mentioned point cloud. The elapsed time within the total volume has been removed has been estimated by dating the initial surface, from which the current rockfall activity started, by means of terrestrial cosmogenic nuclide, 36Cl.
Degut al creixement exponencial de la població durant les últimes dècades, l’avaluació de la perillositat de colades de terra i despreniments i la seva zonificació han esdevingut eines fonamentals pel que fa a la planificació del territori, sobretot en zones muntanyoses. La perillositat degut a fenòmens de vessant va ser definida com la probabilitat d’ocurrència d’un fenomen potencialment danyí en una determinada àrea i per un determinat període de temps. D’aquesta manera, és necessari conèixer la probabilitat d’ocurrència (o freqüència) per cada tipus d’esllavissada i magnitud. L’objectiu d’aquesta tesis és el desenvolupament d’una metodologia objectiva, quantitativa i reproduïble que permeti l’obtenció de les relacions magnitud-freqüència per colades de terra, de mida mitja i gran i per despreniments. Aquest procediment s’ha aplicat a la Vall de Barcedana i la Serra del Montsec per grans colades de terra i despreniments, respectivament. Les dues àrees d’estudi estan situades dins de la Conca de Tremp (Pirineu Oriental). Pel que fa a les colades de terra, s’ha distingit entre 1) reactivacions i 2) vessants intactes. La freqüència de les reactivacions s’ha obtingut a partir de l’anàlisi d’11 grups d’ortofotos que cobreixen des del 1956 al 2013. La magnitud s’ha calculat com l’àrea de les trencades mitjançant la cartografia d’esllavissades i les ortofotos. La relació magnitud-freqüència resultant de les reactivacions ha servit per obtenir la probabilitat de reactivació per un determinat volum. Aquesta ha estat comparada amb la probabilitat de reactivació determinada a partir dels llindars de pluja que han donat lloc a la reactivació de 4 grans esllavissades, també situades dins la Conca de Tremp. Les dates de reactivació han estat aproximades mitjançant la dendrogeomorfologia i els llindars s’han determinat mitjançant l’anàlisi ROC. La susceptibilitat de les primeres trenades s’ha obtingut mitjançant un model determinista anomenat SINMAP. La freqüència per cada classe de susceptibilitat s’ha calculat mitjançant un inventari de primeres trencades identificades al camp i a través d’ortofotos. S’ha desenvolupat un algoritme per tal d’obtenir l’àrea de les colades de terra més grans que la mida del píxel a través de l’agregació automàtic de píxels situats en un mateix vessant i que presenten una mateix classe de susceptibilitat. Finalment, s’ha definit la matriu magnitudfreqüència per la zonificació de la perillositat dels vessants intactes. Pel que fa als despreniments, s’ha definit una metodologia per obtenir la distribució de volums de cicatrius de despreniments d’un penya-segat. S’ha assumit que els volums de cicatrius de despreniments poden ser una primera aproximació dels volum de despreniments. En aquest cas, la distribució de les cicatrius de despreniments s’ha calculat utilitzant un núvol de punts d’alta resolució de la paret obtingut amb un LIDAR terrestre. S’han calculat vàries distribucions de volums per tal de tenir en compte els diferents mecanismes de despreniment i el conseqüent rang de volums despresos. Finalment, s’ha proposat una metodologia per tal de convertir la freqüència estadística (% de volums de cicatrius), calculada en el pas anterior, a freqüència temporal (número anual de volums de cicatrius). Per això, el volum total de material desprès s’ha calculat mitjançant el núvol de punts, mencionat anteriorment. El període de temps durant el qual s’ha desprès tot el volum de material s’ha estimat mitjançant la datació de la superfície inicial a partir de la qual va començar l’actual activitat de despreniments. Aquesta datació s’ha fet mitjançant l’isòtop cosmogenic, 36Cl.
Debido al crecimiento exponencial de la población durante las últimas décadas, la evaluación de la peligrosidad de coladas de tierra y desprendimientos i su zonificación se ha convertido en herramientas indispensables para la planificación del territorio, sobretodo en zonas montañosas. La peligrosidad debido a fenómenos de vertiente fue definida como la probabilidad de ocurrencia de un fenómeno potencialmente dañino en una determinada área y en un determinado período de tiempo. Así, es necesario conocer la probabilidad de ocurrencia (o frecuencia) para cada tipo de deslizamiento y magnitud. El objetivo de esta tesis es el desarrollo de una metodología objetiva, cuantitativa y reproducible que permita la obtención de las relaciones magnitud-frecuencia para coladas de tierra, de tamaño medio y grande y para desprendimientos. Este procedimiento se ha aplicado en Valle de Barcedana y en la Sierra del Montsec para grandes coladas de tierra y desprendimientos, respectivamente. Las dos áreas de estudio están situadas dentro de la Cuenca de Tremp (Pirineo Oriental). En cuanto a las coladas de tierra, se ha distinguido entre 1) reactivaciones y 2) vertientes intactos. La frecuencia de las reactivaciones se ha obtenido a partir del análisis de 11 grupos de ortofotos que engloban des del 1956 hasta el 2013. La magnitud se ha calculado como el área de las roturas mediante la cartografía de deslizamientos y ortofotos. La relación magnitud-frecuencia de las reactivaciones ha permitido obtener la probabilidad de reactivación per un determinado volumen. Esta ha sido comparada con la probabilidad de reactivación determinada a partir de los umbrales de lluvia que han dado lugar a la reactivación de 4 grandes deslizamientos, también situados dentro de la Cuenca de Tremp. Las fechas de reactivación han sido aproximadas mediante la dendrogeomorfología y los umbrales se han determinado mediante el análisis ROC. La susceptibilidad de las primeras roturas se ha obtenido mediante un modelo determinista llamado SINMAP. La frecuencia para cada clase de susceptibilidad se ha calculado mediante un inventario de primeras roturas identificadas en el campo y a través de ortofotos. Se ha desarrollado un algoritmo para obtener el área de las coladas de tierra más grandes que el tamaño del píxel a través de la agregación automática de píxeles situados en una misma vertiente y que presentan una misma clase de susceptibilidad. Finalmente, se ha definido la matriz magnitud-frecuencia para la zonificación de la peligrosidad de las vertientes intactas. En lo que concierne a los desprendimientos, se ha definido una metodología para obtener la distribución de volúmenes de cicatrices de desprendimientos de un acantilado. Se ha asumido que los volúmenes de cicatrices de desprendimientos pueden ser una primera aproximación de los volúmenes de desprendimientos. En este caso, la distribución de las cicatrices de desprendimientos se ha calculado utilizando una nube de puntos de alta resolución de la pared obtenida con un LIDAR terrestre. Se han calculado varias distribuciones de volúmenes para tener en cuenta los diferentes mecanismos de desprendimiento y el consecuente rango de volúmenes desprendidos. Finalmente, se ha propuesto una metodología para transformar la frecuencia estadística (% de volúmenes de cicatrices), calculada en el paso anterior, en frecuencia temporal (número anual de volúmenes de cicatrices). Para esto, el volumen de material desprendido se ha calculado mediante la susodicha nube de puntos. El período de tiempo durante el cual se ha desprendido la totalidad del volumen de material se ha estimado mediante la datación de la superficie inicial a partir de la cual empezó la actual actividad de desprendimientos. Esta datación se ha hecho mediante el isótopo cosmogénico 36Cl.

Ce travail de thèse a consisté à établir une base de données d'éboulements rocheux la plus exhaustive possible (pour des volumes supérieurs à 0,1 m3) pour une paroi rocheuse active dominant l'agglomération grenobloise, en utilisant des données de scanner laser et de photographie. Le site d'étude est une falaise calcaire de plusieurs kilomètres en bordure du massif de la Chartreuse, constituée de deux barres de morphologies différentes, l'une en calcaire lité, l'autre en calcaire massif.Les nuages de points issus du scanner laser permettent de reconstituer la falaise et les compartiments éboulés en 3D. Les données de surface des falaises, ainsi que des informations sur la localisation, les dimensions, le mécanisme de rupture propre à chaque compartiment ont été analysées pour caractériser l'évolution morphologique des deux falaises. Il apparait que la falaise inférieure, dont la morphologie dépend fortement de la fracturation et de l'érosion torrentielle des marnes sous-jacentes, présente une fréquence d'éboulement 22 fois plus importante que la falaise supérieure, de morphologie et pente régulière. De plus, dans la falaise inférieure, le taux d'érosion est 4 fois plus élevé entre 900 et 1000 m d'altitude, qu'entre 1000 et 1100 m. Cela montre que le régime d'érosion de cette falaise est transitoire, alors que celui de la falaise supérieure pourrait être permanent.Les éboulements rocheux détectés ont également été datés par un suivi photographique pendant 2,5 ans. Un suivi quasi-continu (1 photo toutes les 10 min), avec un objectif grand angle a permis de dater 214 éboulements de plus de 0,1 m3. Un suivi mensuel, avec un téléobjectif, a permis de dater 854 éboulements de plus de 0,01 m3. L'analyse de ces deux bases de données montre que la fréquence d'éboulements rocheux peut être 7 fois plus grande lors d'un épisode de gel-dégel que sans évènement météorologique particulier, et 4,5 fois plus grande lors d'un épisode de pluie. De plus, elle devient 26 fois plus grande si l'intensité depuis le début de l'épisode est supérieure à 5 mm/h. A partir de ces résultats, une échelle de 4 niveaux d'aléa a pu être proposée pour la prévision de l'aléa. La base de données plus précise et la définition des épisodes de gel-dégel ont permis de distinguer différentes phases dans un épisode de gel-dégel : refroidissement à température négative, réchauffement à température négative, et dégel (à température positive). Il apparait que les éboulements rocheux se produisent plus fréquemment lors des périodes de réchauffement (à température négative) et de dégel que lors des périodes de refroidissement. Cela suggère que les éboulements sont causés par la dilatation thermique de la glace plutôt que par la dilatation due au changement de phase. Ils peuvent cependant ne se produire que lors du dégel, car la cohésion de l'interface roche-glace peut être suffisante pour tenir le bloc jusqu'à la fonte de la glace. Des expériences in situ et en laboratoire ont permis de mesurer la pression de glace dans une fissure avec écoulement d'eau. Elles montrent que la glace formée par accrétion (gel de gouttes ou films d'eau) n'exerce pas de pression sur les parois rocheuses
Using laser scanner data, an exhaustive rockfall database (for volume larger than 0.1 m3) has been established for a rockwall located near the town of Grenoble (France). The study site is a long double cliff, on the eastern border of the Chartreuse Massif. The two cliffs consist respectively of thinly bedded and massive limestone, which show different structures, morphologies and rockfall activities.The 3D point clouds obtained by laser scanner allow to detect and model the fallen compartments in 3D. Information about cliff surface, and localization, dimensions, failure mechanism for each compartment were obtained and analyzed in order to characterize the morphological evolutions of the two cliffs. It appears that the morphology and the slope of the lower cliff is related to fracturing and torrential erosion which occurs in the marls below the cliff. The rockfall frequency for this lower cliff is 22 times higher than for the upper cliff. Moreover, in the lower cliff the erosion rate is at least 4 times higher for an elevation between 900 and 1000 m than between 1000 and 1100 m. These results show that the erosion process in the lower cliff is in a transient state, whereas it could be in a steady state in the upper cliff. The morphology and the slope of the upper cliff is more regular than for the lower cliff.Rockfalls have been dated by photographic surveys during 2.5 years. A near-continuous survey (1 photo each 10 mn) with a wide-angle lens have allowed dating 214 rockfalls larger than 0.1 m3, and a monthly survey with a telephoto lens, dating 854 rockfalls larger than 0.01 m3. The analysis of the two data bases shows that the rockfall frequency is 7 times higher during freeze-thaw episodes than without meteorological event, and 4.5 times higher during rainfall episodes. Moreover, it becomes 26 times higher when the mean rainfall intensity (since the beginning of the rainfall episode) is higher than 5 mm/h. Based on these results, a 4-level hazard scale has been proposed for hazard prediction. The more precise data base and freeze-thaw episode definition make it possible to distinguish different phases in freeze-thaw episodes: negative temperature cooling periods, negative temperature warming periods and thawing periods. It appears that rockfalls occur more frequently during warming and thawing periods than during cooling periods. It can be inferred that rockfalls are caused by thermal ice dilatation rather than by dilatation due to the phase transition. But they may occur only when the ice melt, because the cohesion of the ice-rock interface can be sufficient to hold the failed rock compartment until the ice melt. The formation of ice in rock cracks has been studied in the field and in laboratory to highlight its influence on rockfall triggering. It has been shown that ice forming by an accretion process (freezing of water drops) doesn't exert a pressure on the crack walls

La haute montagne est un terrain particulièrement sensible aux variations climatiques. La hausse de température depuis plusieurs décennies a un fort impact sur les parois du massif du Mont Blanc : la dégradation du permafrost s’y traduit par une activité gravitaire majeure. Une augmentation du nombre d'écroulements (>100 m3) liés à des périodes chaudes a en effet été mis en évidence à plusieurs échelles de temps, lors des étés particulièrement chauds de 2003 et 2015 comme au cours des trois dernières décennies. La fréquence des écroulements dans le massif devrait continuer à s’accroitre avec l’augmentation de la température au 21e siècle.En revanche, la fréquence des écroulements dans le massif antérieurement à la fin du Petit Âge Glaciaire (PAG) est très largement inconnue. Pendant l'Holocène voire le Tardiglaciaire, les écroulements dans le massif du Mont Blanc ont-ils également été favorisés par les hausses de température ? Pour répondre à cette question, cette thèse poursuit quatre objectifs :i. Dater un grand nombre d'écroulements dans la partie centrale du massif pour comprendre leur distribution pendant l'Holocène et le Tardiglaciaire. L'âge des niches d’arrachement est obtenu par datation cosmogénique.ii. Vérifier les possibles corrélations entre périodes à forte occurrence d’écroulements et périodes climatiques post-glaciaires.iii. Quantifier le volume des écroulements par reconstruction 3D de la forme des blocs écroulés, et étudier la relation entre volumes écroulés et périodes climatiques.iv. Etudier la relation entre âge d'exposition et couleur des niches d’arrachement quantifiée avec la spectroscopie de réflectance.Un total de 70 surfaces a été échantillonné dans les parois du massif au cours de trois campagnes de terrain en 2006, 2011, et 2015-2016. Les âges d'exposition de 63 surfaces ont été obtenus, compris entre 30 ± 20 ans et 100.50 ± 8.50 ka. Trois groupes d’âges peuvent être corrélés aux périodes climatiques chaudes que sont : les Périodes Chaudes de l'Holocène moyen (7.50 – 5.70 ka), l'Optimum de l'âge de Bronze (3.35 – 2.80 ka) et le Période Chaude Romaine (2.35 – 1.75 ka) ; un quatrième groupe d'âges est daté entre 4.91 et 4.32 ka. Le groupe d'âges le plus nombreux, entre 1.09 ka et l'Actuel, aux volumes généralement réduits, est interprété comme représentatif de l'activité gravitaire annuelle du massif avec le climat actuel.Les données spectrales des échantillons datés ont permis de développer un index de la couleur du granite (GRIGRI) par combinaison des valeurs de réflectivité de deux longueurs d'onde différentes. Cet index est corrélé avec l'âge d'exposition (R=0.861) ; il a permis de proposer la datation de 10 échantillons d'âge inconnu à partir de leurs caractéristiques spectrales
High mountain is particularly sensitive to climate variations. The raising temperature that is currently taking place due to climate change has a strong impact on the Mont Blanc massif rock walls: a higher rockfall (>100 m3) occurrence has been noticed, caused by permafrost thawing. The raising in number of rockfalls has been successfully correlated to warm periods at different timescales, e.g., during extreme warm episodes like the 2003 and 2015 heat waves, and during the last 30 years. According to the expected raising temperatures, during the 21st century rockfall occurrence should continue to rise.Rockfall frequency in the Mont Blanc massif before the Little Ice Age is still largely unknown. During Lateglacial and Holocene, high occurrence has been related to warm periods as well? In order to answer this question, this PhD thesis has four aims:i. To date several rockfalls having taken place in the central part of the Mont Blanc massif, in order to understand their frequency during Lateglacial and Holocene. Exposure age of rockfall scars is obtained using Terrestrial Cosmogenic Nuclide dating.ii. To verify possible relationships between high rockfall occurrence periods and post-glacial climate periods.iii. To quantify rockfall volumes by means of 3D reconstruction of the rockfall shapes, to explore the possible relationship between cumulate volumes and climate periods.iv. To study the relationship between exposure ages and colours of rock surfaces. Colours are quantified by reflectance spectroscopy.A total of 70 rock surfaces have been sampled during three field campaigns that took place in 2006, 2011 and 2015-2016. 63 exposure ages were obtained, ranging 30 ± 20 a to 100.50 ± 8.50 ka. Three age clusters can be correlated to warm periods, corresponding to: two Holocene Warm Periods (7.50 – 5.70 ka), the Bronze Age Optimum (3.35 – 2.80 ka) and the Roman Warm Period (2.35 – 1.75 ka). A fourth age cluster has been detected with ages ranging 4.91 – 4.32 ka. The biggest cluster, ranging 1.09 ka – recent, shows rather small volumes. This is interpreted as the normal erosion activity corresponding to the current climate.The samples reflectance spectra allowed to develop a granite colour index (GRIGRI) by combining the values of two different wavelengths. This index is correlated to the samples exposure age (R = 0.861), and has been used to date the exposure age of 10 samples where Terrestrial Cosmogenic Nuclide dating failed

Parmi les mouvements de terrain, les éboulements rocheux restent le danger le plus imprévisible et le plus fréquent en région alpine. Dans un contexte d'urbanisation croissante des régions montagneuses, les éboulements représentent un risque croissant pour les communautés locales et les infrastructures. Cette thèse vise à développer une association pertinente de méthodes pour la surveillance des éboulements en couplant des mesures de relief à un suivi sismologique, afin d’améliorer la compréhension de la dynamique des éboulements. Ce travail a été principalement réalisé dans le massif de la Chartreuse (Isère, Alpes Françaises), et en particulier sur deux falaises, le mont Saint-Eynard et le mont Granier. Par photogrammétrie, nous avons obtenu des Modèles Numériques de Terrain (MNTs) des falaises. Ce suivi nous a permis de réaliser des inventaires de chutes de blocs et des analyses de fréquence d'occurrence. Cela nous a également fourni des informations sur les emplacements des éboulements ainsi que leurs configurations structurales. L’association des MNTs et du suivi sismique des éboulements nous a permis d’étudier les relations entre les propriétés des éboulements (emplacement, volume, géométrie, propagation, etc.) et le signal sismique induit par ceux-ci. Les caractéristiques des signaux sismiques (durée et énergie, contenu fréquentiel, forme de l’enveloppe) diffèrent selon le mode de propagation des évènements (écoulement en masse, chute libre, glissement, rebondissement, …). Une sélection d’évènements ayant le même type de propagation permet d’obtenir une caractérisation plus précise des propriétés des éboulements que si l’on mélange différents types d'événements. Dans le cas d’éboulements subissant une chute libre, nous avons analysé le signal sismique des phases de détachement et du premier impact. Nous avons obtenu des relations entre certains paramètres des signaux sismiques et l'énergie potentielle des éboulements, leur hauteur de chute libre ou leur volume. Pour les événements de type écoulement en masse, nous avons observé une loi d'échelle entre l'énergie sismique d'un éboulement et son volume. En couplant les MNTs et les enregistrements sismiques, nous sommes ainsi en mesure de reconstruire le déroulement des éboulements avec une datation précise et une estimation de volume correcte. Des lâchers contrôlés de blocs ont été réalisés en laboratoire et in-situ pour élargir nos observations sur les éboulements de falaise
Amongst mass wasting events, rockfalls remain the most unpredictable and the most frequent hazard in the alpine region. In a context of growing urbanization in mountainous regions, rockfalls represent an increasing risk for local communities and infrastructures. This thesis aims to develop an association of relevant methods for rockfall monitoring. One objective of this thesis is to associate topography measurement and seismological monitoring in order to improve significantly in understanding rockfalls dynamics. This work was mainly carried out in the Chartreuse massif (Isère, French Alps), and in particular two cliffs, Mount Saint-Eynard and Mount Granier. Using photogrammetry, we acquired diachronic Digital Elevation Models (DEMs) of the cliffs. Such monitoring enables us to carry out rockfall inventories and occurrence frequency analysis. It also provides us information on rockfall locations and their structural configurations. Combining DEMs and rockfall seismic monitoring allowed us to study relations between rockfall properties (location, volume, geometry, propagation, etc.) and the induced seismic signal. Characteristics of the seismic signal (duration and energy, frequency content, envelope shape) vary depending on the event propagation mode (mass-flow, free-fall, sliding, bouncing …). Selecting events with the same propagation type provides a more accurate characterization of rockfalls properties than when mixing different types of events. For free-falling rockfalls, we analyze the seismic signal of the detachment phases and first impacts. We found relations between seismic signals parameters and rockfalls potential energy, free-fall heights, and volumes. For mass-flow type events, we found a scaling law between rockfalls seismic energy and their volumes. By coupling DEMs and seismic records, we can reconstruct rockfall sequence with accurate timing and correct volume estimations. Controlled block releases were realized in laboratory and on-site to widen our observations on rockfall events

The Rockfall Management System developed for Tennessee DOT (TennRMS)integrates a customized rockfall risk rating system, web-based GIS application, and rockfall database to provide a robust single interface for interacting with rock slope information. The system should prove to be a valuable tool for the proactive management of rock slopes. The most important use of the system will be to identify and prioritizing rock slopes with the greatest potential for rockfall in order to provide decision makers with all the necessary information they need to plan remediation efforts. Over time, TennRMS can be used to track costs and effectiveness of different remediation methods used on problem rock slopes. Three papers have been developed for publication in peer reviewed journals. The papers describe the work done in support of developing Tennessee's Rockfall Management System (TennRMS) and its components. The system can be described by its conceptual framework and actual implemented components. Asset management incorporating risk & decision analysis and knowledge management makes up the conceptual framework. The system components include a field data collection system using PDA's, a rockfall database and a web-based GIS interface. The papers articulate the development and implementation of the various components and to provide a detailed review of rockfall management systems as implemented over the past 15 years.
Ph. D.

Rockfall from rock slopes adjacent to roadways is a major hazard and poses a problem for transportation agencies across the country. The state of Tennessee has implemented the Tennessee Rockfall Management System (RMS) as a means of reducing the liabilities associated with rockfall hazard. It utilizes digital data acquisition via PDAs coupled with distribution via an expandable web-based GIS database. The Tennessee Rockfall Hazard Rating System (RHRS) is part of the Tennessee RMS and assigns a numeric hazard rating according relative hazard for all slopes identified as having a high potential for delivering rock blocks onto Tennessee Department of Transportation maintained roadways. The Tennessee RHRS uses standard rock slope failure mechanisms (planar failure, wedge failure, topple failure, differential weathering, and raveling) along with the site and roadway geometry to assess the rockfall hazard of an individual slope. This study suggests methods that will expedite fieldwork, including an informational guide on how to properly identify individual failure mechanisms in the field. Also, the study examines the current method of scoring abundance and suggests an alternative, multiplicative approach. The alternative of using a multiplicative abundance is considered and its results summarized.
Master of Science

Rockfalls exert a first-order control on the rate of rock wall retreat on mountain slopes and on coastal rock cliffs. Their occurrence is conditioned by a combination of intrinsic (resisting) and extrinsic (driving) processes, yet determining the exact effects of these processes on rockfall activity and the resulting cliff erosion remains difficult. Although rockfall activity has been monitored extensively in a variety of settings, high-resolution observations of rockfall occurrence on a regional scale are scarce. This is partly owing to difficulties in adequately quantifying the full range of possible rockfall volumes with sufficient accuracy and completeness, and at a scale that exceeds the influence of localised controls on rockfalls. This lack of insight restricts our ability to abstract patterns, to identify long-term changes in behaviour, and to assess how rock slopes respond to changes in both structural and environmental conditions, without resorting to a space for-time substitution. This thesis develops a workflow, from novel data collection to analysis, which is tailored to monitoring rockfall activity and the resulting cliff retreat continuously (in space), in 3D, and over large spatial scales (> 10^4 m). The approach is tested by analysing rockfall activity and the resulting erosion recorded along 20.5 km of near-vertical coastal cliffs, in what is considered as the first multi-temporal detection of rockfalls at a regional-scale and in full 3D. The resulting data are then used to derive a quantitative appraisal of along-coast variations in the geometric properties of exposed discontinuity surfaces, to assess the extent to which these drive patterns in the size and shape of the rockfalls observed. High-resolution field monitoring is then undertaken along a subsection of the coastline (> 10^2 m), where cliff lithology and structure are approximately uniform, in order to quantify spatial variations in wave loading characteristics and to relate these to local morphological conditions, which can act as a proxy for wave loading characteristics. The resulting rockfall inventory is analysed to identify the characteristics of rock slope change that only become apparent when assessed at this scale, placing bounds on data previously collected more locally (< 10^2 m). The data show that spatial consistencies in the distribution of rockfall shape and volume through time approximately follow the geological setting of the coastline, but that variations in the strength of these consistencies are likely to be conditioned by differences in local processes and morphological controls between sites. These results are used to examine the relationships between key metrics of erosion, structural, and morphological controls, which ultimately permits the identification of areas where patterns of erosion are dominated by either intrinsic or extrinsic processes, or a mixture of both. Uniquely, the methodologies and data presented here mark a step-change in our ability to understand the competing effects of different processes in determining the magnitude and frequency of rockfall activity, and the resulting cliff erosion. The findings of this research hold considerable implications for our understanding of rockfalls, and for monitoring, modelling, and managing actively failing rock slopes.

Les chutes de blocs constituent un aléa naturel majeur dans les Alpes françaises en raison de leur probabilité d'occurrence spatiale et temporelle très élevée. Les forêts peuvent constituer une solution naturelle et efficace pour atténuer ce phénomène tout en protégeant les populations et leurs infrastructures. Cependant, ce service écosystémique peut être perturbé par d'autres aléas naturels comme les feux de forêts, susceptibles d'être plus fréquents et intenses dans le contexte actuel et futur de changements climatiques.Cette thèse propose ainsi d'évaluer les effets des incendies sur la capacité de protection des forêts contre les chutes de blocs dans les Alpes françaises.Une méthodologie pour évaluer la capacité de protection d'une forêt contre les chutes de blocs est d'abord développée et consiste à utiliser des simulations de propagation de chutes de blocs réalisées sur 3886 placettes forestières des Alpes françaises pour calculer trois indicateurs quantitatifs évaluant la réduction de la fréquence (BARI), de l'intensité (MIRI) et la réduction globale (ORPI) de l'aléa chutes de blocs dues à la présence d'une forêt. Ces indicateurs sont utilisés pour identifier les variables forestières prépondérantes pour évaluer la capacité de protection : la longueur boisée sur le versant, la surface terrière et le diamètre moyen. Les peuplements présentant une distribution hétérogène des diamètres et composés de plusieurs essences offrent généralement une meilleure protection que les peuplements monospécifiques et réguliers, soulignant ainsi l'influence de la diversité forestière. Cette thèse montre ainsi que les taillis présentent les capacités de protection les plus élevées, suivis par les futaies feuillues et les futaies mixtes ; les peuplements résineux venant en dernier.Les évolutions spatiales et temporelles des conditions climatiques favorables aux incendies, étudiées sur la période 1959-2015, révèlent un contraste majeur entre les Alpes du Sud qui ont connu une forte augmentation (en intensité, fréquence, durée et saisonnalité) surtout à haute altitude, et les Alpes du Nord, où une légère hausse est observée à basse altitude, mais aucune tendance significative n'est observée à haute altitude. Ces résultats sont ensuite utilisés pour définir trois types de feux (d'hiver, d'été moyen et d'été très sec) pour lesquels la mortalité post-incendie est étudiée à l'échelle de l'arbre et du peuplement forestier. Ces analyses montrent que seuls les feux d'été sont susceptibles d'affecter significativement les peuplements, en particulier à basse altitude où les peuplements feuillus (notamment les taillis) dominent.L’effet des incendies sur la capacité de protection des forêts est évalué en comparant les simulations de propagation de chutes de blocs sans feu aux simulations après chaque type de feu pour lesquelles les arbres avec une forte probabilité de mortalité post-feu ne sont pas pris en compte. Les valeurs de ORPI pour chaque placette forestière et chaque type de feu sont ainsi calculées et comparées au scénario de référence sans feu, permettant ainsi d'évaluer quantitativement la réduction de la capacité de protection. Les peuplements de basse altitude, soumis à des conditions climatiques plus chaudes et sèches, présentent des réductions de la capacité de protection après des feux d'été de l'ordre de 60 à 100 %. Il s'agit principalement de taillis et de futaies feuillues. À plus haute altitude, la réduction est de l'ordre de 30 à 65 %.En conclusion, ce travail de thèse propose une méthode originale pour quantifier la capacité de protection d'une forêt contre les chutes de blocs avant et après un incendie et alimente les connaissances sur ces deux aléas naturels et les risques associés. L'analyse multi-aléas conduite en fin de thèse permet d'appréhender les effets cascades potentiels à l'échelle du peuplement forestier et de quatre territoires bioclimatiquement homogènes des Alpes françaises
Rockfalls are a major natural hazard in the French Alps due to their high probability of spatial and temporal occurrence. Forests constitute an efficient nature-based solution to mitigate this hazard while protecting human lives and assets. However, this ecosystem service may be disrupted by others natural hazards such as wildfires likely to be more frequent and intense in the current and future context of climate changes.This PhD thesis proposes to assess the effects of fires on the protection capability of forests against rockfalls in the French Alps.A methodology to evaluate the protection capability of a forest against rockfalls is first developed. It consists in modeling rockfalls propagations on 3886 forest plots taken in the French Alps to calculate three quantitative indicators that assess the reduction of the frequency (BARI), the intensity (MIRI) and the overall reduction (ORPI) of rockfalls due to the presence of a forest. These indicators are used to identify the predominant forest variables for assessing the protective effect: the length of forest along the slope, the basal area and the mean diameter. Forest stands with a heterogeneous distribution of diameters and made up of several tree species generally offer a better protection than monospecific and regular stands, thus underlining the influence of forest diversity. This work shows that coppices have the highest protection capabilities, followed by hight stands dominated by deciduous species and mixed stands; coniferous stands coming last.Spatio-temporal trends in fire weather in the French Alps are investigated over the period 1959-2015 and reveal a major contrast between Southern Alps which experienced a strong increase (in intensity, frequency, duration and seasonality) especially at high elevation, and Northern Alps, where a slight increase at low elevation and no significant trends at high elevation are observed. These results are then used to define three types of fires (winter, summer, and dry summer) for which post-fire tree mortality is studied at the tree and forest stands levels. These analyses show that only summer fires are likely to significantly affect the forest ecosystems, particularly at low elevations where deciduous stands (especially coppice) dominate.The effect of fires on the protection capabilities of forests is assessed by comparing rockfalls propagation simulations without fire to simulations after each type of fire in which the trees with a high post-fire mortality are not taken into account. The ORPI values for each forest plot and fire type are thus calculated and compared to the reference scenario without fire thus making it possible to quantitatively assess the reduction of the protection capabilities. Low elevation stands, subject to warmer and drier climatic conditions, show reductions of the protective effect in the range 60-100%. It mainly concerns coppices and deciduous stands. At high elevation, the reduction is in the range 30- 65%.In conclusion, this PhD thesis proposes an original method to quantify the protection capabilities of a forest against rockfalls before and after a fire and improve the knowledge of these two natural hazards and their associated risks. The multi-hazard analysis conducted at the end of the thesis makes it possible to understand the potential cascading effects in the main forest types and for four bioclimatically homogeneous territories of the French Alps

Computer simulation of rockfalls has been widely used in rockfall analysis in recent years, and the coefficient of restitution is an important parameter input that is difficult to determine. Aimed at finding an easy solution to this problem, three stages of laboratory and field tests have been carried out. Rockfall trajectory analysis at a specific site has been done as an application to verify the method developed. In the first stage of laboratory testing, quasi-spherical rock "'balls" made from different rock samples were dropped from 1 m onto polished rock slabs that were clamped on a concrete deck, which can be set to different slope angles. A high-speed video camera was used to record the impact processes, and normal and tangential coefficients of restitution were calculated from the video records. The results show a linear relationship between the normal restitution coefficient and the Schmidt hammer numbers of both the rock slabs and the falling rock "balls", and the slope angle. An empirical equation was then established to calculate the normal coefficient of restitution from those three parameters. However, the correlations between the tangential coefficient of restitution and the above parameters are poor, indicating that the tangential coefficient of restitution is not adequately determined by such rock properties. The second stage of laboratory testing was under more practical conditions. Three different rough rock blocks were used as rock slopes. Angular rock boulders were dropped from different heights onto the rock blocks, and a rock "ball" was also used to make a comparison. The results show that the normal coefficients of restitution from impacts of angular rocks are much smaller than those of rock "'balls", and have a linear correlation with those calculated from the empirical equation obtained by the earlier test. Tests on beds of gravel, soil, rock fragments and sand have also been carried out to obtain the coefficients of restitution of those materials. Finally, field tests have been carried out at a quarry site in Lyttelton Basalt rock boulders of about 0.3 m in diameter were dropped from about 4 m onto rock and debris slopes using an excavator. The values of restitution coefficients obtained are similar to those from laboratory tests but larger than those calculated from the empirical equations due to the effect of weathering and surface roughness of rocks in the field on the Schmidt hammer measurement. Forty basalt boulders were then rolled down a bench slope of about 16 m, three cameras were used to record the rockfall processes. Two different rockfall simulation programs (CRSP and RocFall) were used to simulate the rockfall processes. The simulated bounce heights and velocities from CRSP are close the field trial, while those from RocFall are smaller than the field results. Comprehensive rockfall analysis has been carried out for the Marine apartments, Sumner, where a steep cliff of 35-45 m represents potential rockfall hazards to a car park and proposed buildings at the base. Site investigation, rockfall simulation and risk assessment have been carried out for the site. The results show that without any protection measures, a majority of rocks from the cliff face reach the edge of the car park. The probability of an accident at the car park is moderate (1 in 195 years), while the probability of fatality at the car park is low (8.69* 10-6) and acceptable under the proposed risk criteria for "Major Civil Engineering Projects".

Current understanding of the nature of rockfall and their controls stems from the capabilities of slope monitoring. These capabilities are fundamentally limited by the frequency and resolution of data that can be captured. Various assumptions have therefore arisen, including that the mechanisms that underlie rockfall are instantaneous. Clustering of rockfall across rock faces and sequencing through time have been observed, sometimes with an increase in pre-failure deformation and pre-failure rockfall activity prior to catastrophic failure. An inherent uncertainty, however, lies in whether the behaviour of rockfall monitored over much shorter time intervals (Tint) is consistent with that previously monitored at monthly intervals, including observed failure mechanisms, their response to external drivers, and pre-failure deformation. To address the limitations of previous studies on this topic, 8 987 terrestrial laser scans have been acquired over 10 months from continuous near-real time monitoring of an actively failing coastal rock slope (Tint = 0.5 h). A workflow has been devised that automatically resolves depth changes at the surface to 0.03 m. This workflow filters points with high positional uncertainty and detects change in 3D, with both approaches tailored to natural rock faces, which commonly feature sharp edges and partially occluded areas. Analysis of the resulting rockfall inventory, which includes > 180 000 detachments, shows that the proportion of rockfall < 0.1 m3 increases with more frequent surveys for Tint < ca. 100 h, but this trend does not continue for surface comparison over longer time intervals. Therefore, and advantageously, less frequent surveys will derive the same rockfall magnitude-frequency distribution if captured at ca. 100 h intervals as compared to one month or even longer intervals. The shape and size of detachments shows that they are more shallow and smaller than observable rock mass structure, but appear to be limited in size and extent by jointing. Previously explored relationships between rockfall timing and environmental and marine conditions do not appear to apply to this inventory, however, significant relationships between rockfall and rainfall, temperature gradient and tides are demonstrated over short timescales. Pre-failure deformation and rockfall activity is observed in the footprint of incipient rockfall. Rockfall activity occurs predominantly within the same ca. 100 h timescale observed in the size-distribution analysis, and accelerated deformation is common for the largest rockfall during the final 2 h before block detachment. This study provides insights into the nature and development of rockfall during the period prior to detachment, and the controls upon it. This holds considerable implications for our understanding of rockfall and the improvement of future rockfall monitoring.

Mountainous areas are prone to natural hazards like rockfalls. Among the many countermeasures, rockfall protection barriers represent an effective solution to mitigate the risk. They are metallic structures designed to intercept rocks falling from unstable slopes, thus dissipating the energy deriving from the impact. This study aims at providing a better understanding of the response of several rockfall barrier types, through the development of rather sophisticated three-dimensional numerical finite elements models which take into account for the highly dynamic and non-linear conditions of such events. The models are built considering the actual geometrical and mechanical properties of real systems. Particular attention is given to the connecting details between the structural components and to their interactions. The importance of the work lies in being able to support a wide experimental activity with appropriate numerical modelling. The data of several full-scale tests carried out on barrier prototypes, as well as on their structural components, are combined with results of numerical simulations. Though the models are designed with relatively simple solutions in order to obtain a low computational cost of the simulations, they are able to reproduce with great accuracy the test results, thus validating the reliability of the numerical strategy proposed for the design of these structures. The developed models have shown to be readily applied to predict the barrier performance under different possible scenarios, by varying the initial configuration of the structures and/or of the impact conditions. Furthermore, the numerical models enable to optimize the design of these structures and to evaluate the benefit of possible solutions. Finally it is shown they can be also used as a valuable supporting tool for the operators within a rockfall risk assessment procedure, to gain crucial understanding of the performance of existing barriers in working conditions.

Rockfall threaten infrastructure and people throughout the world. Estimating the runout dynamics of rockfall is commonly performed using models, providing fundamental data for hazard management and mitigation design. Modelling rockfall is made challenging by the complexity of rock-ground impacts. Much research has focused on empirical impact laws that bundle the rock-ground impact into a single parameter, but this approach fails to capture characteristics associated with the impact configuration and, in particular, the effects of rock-shape. While it is apparent that particular geological settings produce characteristic rock-shapes, and that different rock-shapes may produce characteristic runout dynamics, these aspects of rockfall are poorly understood. This study has focused on investigating the mechanics behind the notion that different rock-shapes produce characteristic runout dynamics and trajectories. The study combines field data on rockfall runout, trajectory and dynamics, laboratory analogue testing in controlled conditions, and numerical modelling of the influence of rock-shape. Initially rock-shape, deposition patterns and rockfall dynamics were documented at rockfall sites in Switzerland and New Zealand. This informed a detailed study of individual rock-ground impacts on planar slopes in which laboratory-scale and numerical rockfall experiments were combined to isolate the role of rock-shape on runout. Innovatively, the physical experiments captured the dynamics of impacts and runout paths using high speed video tracking and a sensor bundle with accelerometers and gyroscopes. Numerical experiments were performed using a 3-D rigid-body rockfall model that considers rock-shape, and has allowed the variability of rockfall behaviour to be explored beyond the limitations of physical experimentation. The main findings of the study were on understanding rockfall-ground impacts, the influence of rock-shape on rockfall dynamics, and influence of rock sphericity. By measuring velocity, rotational speed, impact and runout character, it has been possible to quantify the variability of individual rock-ground impacts as a function of rock-shape. Investigation of single rebounds reveals that if classical restitution coefficients are applied, $R_n$ values greater than unity are common and rebounds are highly variable regardless of constant contact parameters. It is shown that this variability is rooted in the inherent differences in the magnitudes of the principal moment of inertia of a rock body brought about by rock-shape. Any departure from a perfect sphere induces increased range and variability in rock-ground rebound characteristics. In addition to the popular description of a rock bouncing down slope, rebounds involve the pinning of an exterior edge point on the rock, creating a moment arm which effectively levers the rock into ballistic trajectory as it rotates. Observations reveal that the angle of the impact configuration plays a key role in the resulting rebound, whereby low angles produce highly arched rebounds, while large impact angles produce low flat rebounds. The type of rebound produced has a strong bearing on the mobility of the rocks and their ability to maintain motion over a long runout. The mobility of rocks is also shown to be related to rotation, which is governed by the differences in the principal inertial axes as a function of rock-shape. Angular velocity measurements about each principal inertial axis indicate that rocks have a tendency to seek rotation about the axis of largest inertia, as the most stable state. Rotations about intermediate and small axes of inertia and transitions between rotational axes are shown to be unstable and responsible for the dispersive nature of runout trajectories, which are inherent characteristics of different rock-shapes. The findings of this research demonstrate the importance of rock-shape in rockfall runout dynamics and illustrate how it is essential that the rock-shape is included in rockfall modelling approaches if the variability of rockfall behaviour is to be simulated.

The aim of this thesis has been to model small rockfalls in order to better understand where, when and why they occur. High-resolution monitoring of rock slopes has revealed clustering of rockfalls through space and time, suggesting interactions, whereby one detachment from a rock slope influences the nature of those that follow. This observation contrasts with the more conventional idea of rockfalls as time-independent, discrete events that occur in response to an identifiable trigger. As the processes that give rise to observations of rockfall clustering are not well established, this thesis takes the opportunity to bring together current understanding of the controls on rockfalls with ideas around the progressive development of failure in brittle rock in an attempt to explain these patterns. The representation of these processes at scales comparable to high resolution field monitoring has not previously been attempted. Therefore this thesis has developed an approach using numerical modelling to simulate rockfalls as spatially and temporally-dependent sequences of events, to better explain the underlying mechanisms. This study begins with the analysis of a high-resolution inventory of rockfalls, concentrating on identifying patterns in rockfall occurrence. Analyses of this data reveals patterns of rockfalls that cannot be explained by environmental conditions or local geology alone. Evidence has been collected that demonstrates that rockfalls cluster in space and time, and that through time rockfall scars grow upward and outward in a consistent manner. The results of this analysis are used to inform numerical modelling that explores the mechanics driving small rockfalls, focussing upon the impact of a detachment on the location and timing of future rockfalls. Numerical modelling of idealised rock slope sections was conducted using Slope Model and demonstrated that the timing and location of failure in a rock slope could be considered as a function of accumulated damage, represented by fracture. The results suggest that time-dependent failure and associated mechanisms of stress redistribution and damage generation are one possible explanation for the propagating sequences of contiguous failures observed. Finally, this thesis has taken an exploratory approach to modelling rockfalls through the development of a new deterministic, numerical model that simulates rockfall evolution using cellular automata. This rockfall model allows the patterns and associated underlying mechanics of small rockfalls to be explored in detail using a reduced complexity approach. Critically rockfalls are modelled in a 2.5D slope face perspective to allow both rockfalls and their effects to interact across the rock slope through time. The model operates at a relatively high spatial and temporal resolution to consider the full range of rockfall characteristics that have been observed. The outputs of the model are compared with the two-year monitoring data to address key questions regarding the competing roles of endo- and exogenic forcing on rockfall occurrence. The results of the rockfall modelling shows that a consideration of stress redistribution from small scale rockfalls and time-dependent weakening provides a possible explanation for the size distribution of rockfalls, their location and timing, and the resulting changes to slope profile form as observed in the field. This has implications for how rock slopes are monitored and modelled to determine the potential for future rockfalls to occur.

Thesis (Ph.D.)--Tel Aviv University, Department of Geophysics and Planetary Sciences,
This work was submitted as M.Sc. Thesis to the Department of Geophysics and Planetary Sciences, Tel Aviv University / T.P. "September 2008" At head of title: Tel-Aviv University. Raymond and Beverly Sackler faculty of exact sciences. Includes bibliographical references.

The Canterbury Earthquake Sequence (CES) of 2010-2011 produced large seismic moments up to Mw 7.1. These large, near-to-surface (<15 km) ruptures triggered >6,000 rockfall boulders on the Port Hills of Christchurch, many of which impacted houses and affected the livelihoods of people within the impacted area. From these disastrous and unpredicted natural events a need arose to be able to assess the areas affected by rockfall events in the future, where it is known that a rockfall is possible from a specific source outcrop but the potential boulder runout and dynamics are not understood. The distribution of rockfall deposits is largely constrained by the physical properties and processes of the boulder and its motion such as block density, shape and size, block velocity, bounce height, impact and rebound angle, as well as the properties of the substrate. Numerical rockfall models go some way to accounting for all the complex factors in an algorithm, commonly parameterised in a user interface where site-specific effects can be calibrated. Calibration of these algorithms requires thorough field checks and often experimental practises. The purpose of this project, which began immediately following the most destructive rupture of the CES (February 22, 2011), is to collate data to characterise boulder falls, and to use this information, supplemented by a set of anthropogenic boulder fall data, to perform an in-depth calibration of the three-dimensional numerical rockfall model RAMMS::Rockfall. The thesis covers the following topics: • Use of field data to calibrate RAMMS. Boulder impact trails in the loess-colluvium soils at Rapaki Bay have been used to estimate ranges of boulder velocities and bounce heights. RAMMS results replicate field data closely; it is concluded that the model is appropriate for analysing the earthquake-triggered boulder trails at Rapaki Bay, and that it can be usefully applied to rockfall trajectory and hazard assessment at this and similar sites elsewhere. • Detailed analysis of dynamic rockfall processes, interpreted from recorded boulder rolling experiments, and compared to RAMMS simulated results at the same site. Recorded rotational and translational velocities of a particular boulder show that the boulder behaves logically and dynamically on impact with different substrate types. Simulations show that seasonal changes in soil moisture alter rockfall dynamics and runout predictions within RAMMS, and adjustments are made to the calibration to reflect this; suggesting that in hazard analysis a rockfall model should be calibrated to dry rather than wet soil conditions to anticipate the most serious outcome. • Verifying the model calibration for a separate site on the Port Hills. The results of the RAMMS simulations show the effectiveness of calibration against a real data set, as well as the effectiveness of vegetation as a rockfall barrier/retardant. The results of simulations are compared using hazard maps, where the maximum runouts match well the mapped CES fallen boulder maximum runouts. The results of the simulations in terms of frequency distribution of deposit locations on the slope are also compared with those of the CES data, using the shadow angle tool to apportion slope zones. These results also replicate real field data well. Results show that a maximum runout envelope can be mapped, as well as frequency distribution of deposited boulders for hazard (and thus risk) analysis purposes. The accuracy of the rockfall runout envelope and frequency distribution can be improved by comprehensive vegetation and substrate mapping. The topics above define the scope of the project, limiting the focus to rockfall processes on the Port Hills, and implications for model calibration for the wider scientific community. The results provide a useful rockfall analysis methodology with a defensible and replicable calibration process, that has the potential to be applied to other lithologies and substrates. Its applications include a method of analysis for the selection and positioning of rockfall countermeasure design; site safety assessment for scaling and demolition works; and risk analysis and land planning for future construction in Christchurch.

The research presented in this thesis results from efforts to evaluate current design methodologies for safety benches in surface aggregate quarries. Proper bench design is important for preventing rockfall related accidents and injuries without wasting the reserves held in the benches. An in depth analysis has been performed using the results from 230 rockfall tests conducted at two surface quarries. The goal of this project is to give practitioners the tools they need for improved bench design. Principal Components and Cluster Analysis, techniques not previously applied to rockfall investigations, have been performed on the test data. The results indicate that both are valid analytical methods which show that the factors affecting the rollout distance of a rock are wall configuration, rock dimensions, and rock energy. The test results were then compared to the Ritchie Criteria, Modified Ritchie Criterion, Ryan and Pryor Criterion, Oregon Department of Transportation design charts, and RocFall computer simulations. Analysis shows that the lognormal distribution curves fitted to the test data provide an excellent yet quick design reference. The recommended design method is computer simulation using RocFall because of the ease of simulation and the site specific nature of the program. For the two quarries studied, RocFall analysis showed that 20 ft benches with a 4 ft berm will hold over 95% of rockfalls, a design supported by the field testing. Conducting site-specific rockfall testing is also recommended to obtain realistic input parameters for the simulations and to provide design justification to regulatory agencies.
Master of Science

Solid Energy New Zealand plans to mine a 6 to 10m thick coal seam below the Mt. Augustus and Mt. Fredrick ridgeline at Stockton Mine near Westport, NZ. The coal is covered by up to 30m of overburden, which requires removal to access 4 million tones of high quality coal. However, the Coal Mining Lease boundary (CML) is located just below the basal coal measures and the neighbouring land is owned by the Department of Conservation (DoC). In addition, the neighbouring DoC estate is Powelliphanta Augustus snail habitat. It is necessary to remove the overburden without releasing any material above natural discharge levels onto the DoC land. In order to control the rockfall risk at the site, the largest design-build rockfall protection project in the southern hemisphere was constructed using a high-capacity dynamic rockfall barrier installed along the length of the ridgeline. During the design phase of the project, it was evident that current methods to determine the coefficient of restitution (normal and tangential) are subjectively based on the designer's judgement. Currently, there is limited quantitative information available for the determination of dampening coefficients (restitution coefficients) for use in rockfall computer simulation programs. Accurate parameters are necessary for the design and dimensioning of rockfall protection structures. This project investigates an objective method to calculate these parameters for use in rockfall modelling based on field measurements of the slope. The first stage of the project is a review of current rockfall simulation programs and rockfall mechanics. This is followed by a review of the design of the rockfall protection measures installed at Stockton Mine. The site is revisited and detailed investigations are performed to further classify the slope conditions and observe current ridgeline mining methodology and effectiveness. Included in this are detailed geotechnical investigations of the slope (soil and rock) materials. The majority of the slopes below the ridgeline mining are heavily vegetated. This project investigates the interrelation of rockfall and vegetation. A series of laboratory tests are conducted using rock and soil samples from the ridgeline-mining project. Overburden samples were cut into spheres and cubes to investigate the influence of shape and rockfall trajectory. A rockfall simulation device was fabricated to drop samples of various shapes onto rock slabs and soil beds. The drop test trajectories were filmed using high-speed video recordings and used for rebound calculations. The purpose of these tests was to observe the effect of impact angle (slope angle) and shape on the coefficients of restitution. Also investigated was the influence of soil moisture and density on rockfall impacts. Observations from the field investigations and laboratory experiments were then used to calibrate the original rockfall design parameters at the site. This included comparing several common commercially available rockfall simulation programs for trajectory analysis. Recent rockfall events that have occurred during the ridgeline mining were compared to original estimates of volume and block-size to actual rockfall events (both natural and mining-induced).

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
FUNDAÇÃO DE APOIO À PESQUISA DO ESTADO DO RIO DE JANEIRO
PROGRAMA DE EXCELENCIA ACADEMICA
BOLSA NOTA 10
Este trabalho tem como finalidade comparar e analisar diferentes modelos numéricos na análise do processo de queda de blocos com diferentes geometrias, para que seja possível determinar os riscos à infraestrutura e à população local que este evento pode causar. Foram utilizados o software RAMMS e o programa de modelagem PFC3D para simulação de queda de blocos. O primeiro foi desenvolvido pelo instituto suíço WSL, o software utiliza a dinâmica não suave (nonsmooth), não havendo penetração dos blocos com a superfície, e as leis de contato são feitas por restrições. O segundo utiliza o método dos elementos discretos através de dinâmica de contato suave. Na primeira parte do trabalho foram realizadas simulações de casos simples de queda de blocos para ambos os modelos, a fim de analisar o principal parâmetro do contato rocha-solo de cada programa com o alcance das rochas. O modelo de contato no programa PFC3D utilizado foi o método linear, e depois foi adicionada uma força de resistência ao rolamento para que o modelo conseguisse reproduzir o comportamento de solos mais macios. Os modelos foram simulados para casos reais, primeiro foram aplicados para uma encosta na BR116, onde um evento de deslizamento já tinha ocorrido. Foram realizadas simulações com os dois modelos na região, comparando-os e analisando com os vestígios deixados pelo evento. Outro caso estudado foi o de blocos susceptíveis ao deslizamento no bairro Glória, no município de Petrópolis. E por último, foram criados modelos para analisar o comportamento da vegetação em ambos os modelos. Com os resultados obtidos, conclui-se que o PFC3D consegue simular o processo de queda com melhor precisão através do auxílio da força de resistência ao rolamento. Para ambas simulações, o caso da BR116 e o do bairro Glória, os modelos apresentarem uma mesma tendência quanto a trajetória do bloco, mas melhorias na calibração do modelo linear com resistência ao rolamento precisam ser realizadas para que melhores resultados sejam obtidos. A presença de vegetação se mostrou como um mecanismo muito eficiente para perdas de energia no sistema, diminuindo significativamente a velocidade dos blocos.
The aim of this work is to compare and analyze different numerical models on the rockfall process with different geometries, to determine the risks to the local infrastructure and population. It was used the software RAMMS and the modeling program PFC3D to simulate rockfall events. The first software was developed by the Swiss institute WSL, it uses the nonsmooth dynamics system, it is a dynamic behavior where there is no penetration between the rock and the surface and the contact laws are created by restrictions laws. And the second one uses the discrete element method applying the smooth dynamics system to simulate the event. On the first part of the work, numerical models were created on both models to simulate simple cases of rockfall events, to compare the main soil-rock parameter of both modeling program with the distance reached of the rocks. The contact model used on the PFC3D program was the linear method, and after the first simulations was added a rolling resistance force to the model reproduce soft. Both models were applied to real cases, the BR116 was the first case modeled, where some natural hazards have already happened. The results of the numerical simulations were compared and analyzed. It was also created a model to simulate the rockfall event of the Gloria neighborhood, in Petropolis; rocks that could fall were determined and simulations for those blocks were performed, the deposition area and the blocks trajectory of each model were examined. And finally, it was studied the vegetation effect of each model and its particularities. Through the results, it is possible to conclude that the PFC3D can simulate the rockfall process with better accuracy using the rolling resistance method. For both simulation, the BR116 and the Gloria neighborhood, the models showed the same tendency of the blocks trajectory, but it is necessary to improve the calibration of the rolling resistance coefficient. The existence of the vegetation revealed as a very effect lose energy mechanism on the system, decreasing significantly the velocity of the blocks.

This study proposes a rational process that can be used by the mining engineer to control rockfall by the design of catch bench geometry in surface mines. The problem of rockfall in surface mines is defined and factors causing rockfall are identified. Four civil engineering models that predict rockfall motion are presented and compared to rockfall field tests from eight different test sites. Based on these results, a computer program was written that combines aspects of the two best models. The Ritchie empirical model provides the most conservative result of catch bench width and berm height necessary to contain rockfall on mine slopes. The Colorado Rockfall Simulation Program is used to check the reliability of the design and to permit selection of the minimum catch bench geometry to insure both mine safety and the most economic slope angles.

This thesis is concerned with modelling rockfall parameters associated with cliff collapse debris and the resultant “ramp” that formed following the high peak ground acceleration (PGA) events of 22 February 2011 and 13 June 2011. The Christchurch suburb of Redcliffs, located at the base of the Port Hills on the northern side of Banks Peninsula, New Zealand, is comprised of Miocene-age volcanics with valley-floor infilling marine sediments. The area is dominated by basaltic lava flows of the Mt Pleasant Formation, which is a suite of rocks forming part of the Lyttelton Volcanic Group that were erupted 11.0-10.0Ma. Fresh exposure enabled the identification of a basaltic ignimbrite unit at the study site overlying an orange tuff unit that forms a marker horizon spanning the length of the field area. Prior to this thesis, basaltic ignimbrite on Banks Peninsula has not been recorded, so descriptions and interpretations of this unit are the first presented. Mapping of the cliff face by remote observation, and analysis of hand samples collected from the base of the debris slopes, has identified a very strong (>200MPa), columnar-jointed, welded unit, and a very weak (<5MPa), massive, so-called brecciated unit that together represent the end-member components of the basaltic ignimbrite. Geochemical analysis shows the welded unit is picrite basalt, and the brecciated unit is hawaiite, making both clearly distinguishable from the underlying trachyandesite tuff. RocFall™ 4.0 was used to model future rockfalls at Redcliffs. RocFall™ is a two-dimensional (2D), hybrid, probabilistic modelling programme for which topographical profile data is used to generate slope profiles. GNS Science collected the data used for slope profile input in March 2011. An initial sensitivity analysis proved the Terrestrial Laser Scan (TLS)-derived slope to be too detailed to show any results when the slope roughness parameter was tested. A simplified slope profile enabled slope roughness to be varied, however the resulting model did not correlate with field observations as well. By using slope profile data from March 2011, modelled rockfall behaviour has been calibrated with observed rockfall runout at Redcliffs in the 13 June 2011 event to create a more accurate rockfall model. The rockfall model was developed on a single slope profile (Section E), with the chosen model then applied to four other section lines (A-D) to test the accuracy of the model, and to assess future rockfall runout across a wider area. Results from Section Lines A, B, and E correlate very well with field observations, with <=5% runout exceeding the modelled slope, and maximum bounce height at the toe of the slope <=1m. This is considered to lie within observed limits given the expectation that talus slopes will act as a ramp on which modelled rocks travel further downslope. Section Lines C and D produced higher runout percentage values than the other three section lines (23% and 85% exceeding the base of the slope, respectively). Section D also has a much higher maximum bounce height at the toe of the slope (~8.0m above the slope compared to <=1.0m for the other four sections). Results from modelling of all sections shows the significance of the ratio between total cliff height (H) and horizontal slope distance (x), and of maximum drop height to the top of the talus (H*) and horizontal slope distance (x). H/x can be applied to the horizontal to vertical ratio (H:V) as used commonly to identify potential slope instability. Using the maximum value from modelling at Redcliffs, the future runout limit can be identified by applying a 1.4H:1V ratio to the remainder of the cliff face. Additionally, the H*/x parameter shows that when H*/x >=0.6, the percentage of rock runout passing the toe of the slope will exceed 5%. When H*/x >=0.75, the maximum bounce height at the toe of the slope can be far greater than when H*/x is below this threshold. Both of these parameters can be easily obtained, and can contribute valuable guideline data to inform future land-use planning decisions. This thesis project has demonstrated the applicability of a 2D probabilistic-based model (RocFall™ 4.0) to evaluate rockfall runout on the talus slope (or ramp) at the base of ~35-70m high cliff with a basaltic ignimbrite source. Limitations of the modelling programme have been identified, in particular difficulties with adjusting modelled roughness of the slope profile and the inability to consider fragmentation. The runout profile using RocFall™ has been successfully calibrated against actual profiles and some anomalous results have been identified.

Thesis (Ph. D.)--University of Oregon, 2006.
Typescript. Includes vita and abstract. Includes bibliographical references (leaves 115-137). Also available for download via the World Wide Web; free to University of Oregon users.

Scopo della tesi è l'analisi del rischio da caduta massi con Rockfall Hazard Rating System lungo la SP29 di Sovramonte (BL) e la SP19 di Lamon (BL). Sono stati utilizzati il metodo RHRS originale (Pierson et al., 1990) e il metodo RHRS modificato (P.Santi et al., 2009) per valutare gli aspetti geologici di dodici sezioni soggette a distacco di roccia insieme alle caratteristiche stradali. Con i punteggi ottenuti dallo studio di ogni sezione si è infine riusciti a fornire una scala di priorità per gli interventi di sistemazione.

Les chutes de pierres sont l'un des processus géomorphologiques les plus courants dans les milieux à forte pente. Malgré leur volume limité, les chutes de pierres constituent un danger important, en raison de leur évolution rapide, de leur vitesse élevée et de l'énergie d'impact. Leur caractère imprévisible peut être problématique lorsque l'on souhaite étudier en détail leur dynamique et leurs facteurs de déclenchement dans des conditions naturelles. L'influence relative des précipitations, de la fonte des neiges, de la température ou des cycles de gel-dégel est depuis longtemps reconnue, notamment grâce à des méthodes de surveillance des parois à moyen terme. A très haute altitude, des relations sans équivoque ont été établies entre l'augmentation de l'activité des chutes de pierres, le dégel du pergélisol et le réchauffement climatique. En revanche, en dessous de la limite du pergélisol, la rareté persistante de bases de données exhaustives et précises rend nos connaissances encore lacunaires. Au cours des deux dernières décennies, la dendrogéomorphologie - une approche basée sur l'analyse des dommages infligés aux arbres après des impacts d'éboulement - a été utilisée pour combler certaines limites inhérentes aux archives historiques. Paradoxalement, ces reconstitutions n'ont que rarement été comparées aux données climatiques afin de déterminer précisément les facteurs météorologiques déclencheurs ou pour détecter les influences du réchauffement climatique sur l'activité des chutes de pierres.Dans ce contexte, cette thèse vise à proposer des recommandations méthodologiques pour optimiser les stratégies d'échantillonnage afin de quantifier précisément les incertitudes des reconstructions dendrogéomorphologiques dans le temps. Nos résultats montrent que la cartographie à haute résolution des tiges sur les sites étudiés combinée à une sélection rigoureuse des espèces d'arbres situées à proximité des falaises améliore la robustesse des reconstitutions sur les parcelles étudiées à Saint-Guillaume (peuplement forestier mixte, massif du Vercors, Alpes françaises) et à Valdrôme (peuplements forestiers monospécifiques plantés, massif du Diois, Alpes françaises).Dans un second temps, nous nous servons des reconstructions obtenues et des réanalyses SAFRAN pour identifier les déclencheurs météorologiques des événements de chutes de pierres. A l'échelle interannuelle, nos résultats montrent que les précipitations estivales et les événements pluvieux intenses sont les principaux facteurs de l'activité des chutes de pierres sur les deux sites, alors qu'aucun impact clair des températures ou des cycles de gel-dégel n'a pu être détecté.Enfin, nous comparons les fluctuations décennales existantes dans les deux reconstructions dendrogéomorphologiques avec les séries climatiques disponibles pour la période 1959-2017, dans le but de détecter les impacts potentiels du réchauffement climatique sur l'activité des chutes de pierres. Dans le massif du Vercors, nous expliquons l'augmentation de l'activité des chutes de pierres observée depuis 1959 par une recolonisation forestière rapide et par la sur-représentation des jeunes arbres, plus sensibles, plutôt que par le changement climatique. Dans le massif du Diois, l'absence de tendance significative suggère qu'une légère augmentation de l'activité n'est pas soutenu par les données existantes. Cependant, la faible robustesse des modèles de régression multiple utilisés ici, l'augmentation limitée de la température sur les sites d'étude et le caractère incomplet de nos reconstructions dendrogémorphologiques suggèrent que ces résultats doivent être traités avec prudence.Au total, cette thèse démontre clairement la valeur ajoutée de la dendrogéomorphologique pour reconstruire l'activité passée des chutes de pierres, évaluer les conditions météorologiques propices aux déclenchement de cet aléa et détecter les impacts potentiels des changements environnementaux sur la dynamique des processus
Rockfalls are one of the most common geomorphological processes in the steeply sloping environments. Despite their limited volumes, rockfalls pose a significant hazard, due to their rapid evolution, high velocity and impact energy, but their unpredictable occurrence hinders detailed investigation of their dynamics and drivers under natural conditions. As the relative influence of rainfall, snowmelt, temperature, or freeze–thaw cycles have long been identified, based on medium-term monitoring methods, as the main drivers of rockfall activity, increasing rockfall hazards triggered by climate change are a major concern expressed both in scientific and non-scientific media.At high altitude sites, unequivocal relationships have been established between heightened rockfall activity, permafrost thawing and global warming. By contrast, below the permafrost limit, in the absence of longer-term assessments of rockfall triggers and possible changes thereof, our knowledge of rockfall dynamics remains still lacunary as a result of the persisting scarcity of exhaustive and precise rockfall databases.Over the last two decades, dendrogeomorphology – based on the analysis of damage inflicted to trees after rockfall impacts – has been used to overcome certain limitations inherent to historical archives and reconstructions of rockfall activity have been developed. Paradoxically, tree-ring reconstructions have only rarely been compared with climatic data to precisely constrain the potential meteorological triggers of process activity or to detect potential influences of global warming mostly due to the absence of clear recommendations to derive reconstructions that optimally capture the climatic signal in rockfall-prone environments.In this context, this PhD thesis first aims at proposing clear methodological guidelines to optimize sampling strategies of trees so as to precisely quantify uncertainties in dendrogeomorphic reconstructions back in time. Our results clearly evidence that the high-resolution mapping of stems on the studied combined with a careful selection of tree-species located at the vicinity of the cliffs improve the robustness of our reconstructions at the Saint-Guillaume (mixed forest stand, Vercors massif, French Alps) and Valdrôme (monospecific planted forest stands, Diois massif, French Alps) studied plots.In the second part, we capitalize on rockfall activity derived from optimized reconstructions and on the high-spatio-temporal resolution of the SAFRAN reanalyses, to precisely identify the meteorological triggers of rockfall events. At the interannual scale, our results evidence that summer precipitations and intense rainfall-events are the main drivers at both sites while no clear impact of temperature or freeze-thaw cycles could be detected.Finally, we compare decadal fluctuations existing in both tree-ring records with climatic series available for the period 1959-2017 with the purpose to detect the potential impacts of global warming on rockfall activity. In the Vercors massif, we explain increasing rockfall activity observed in the reconstruction since 1959 by a rapid forest recolonization and the overrepresentation of young sensitive trees rather than by climate change. In the Diois massif, the absence of significant trend suggests that a premature warning of increasing rockfall hazard, is not supported by the existing data. Yet, the weak robustness of the multiple regression models used here, the limited increase of temperature at the study sites and the incompleteness of our tree-ring reconstructions suggest that these results have to be treated with cautiously. All in all, this PhD thesis clearly demonstrates the added-value of the dendrogeomorphic approach to reconstruct rockfall activity, assess the meteorological driver of past events as well as to detect the potential impacts of environmental changes on the process dynamics

In questa tesi è stata valutata la pericolosità e quindi il relativo rischio da crollo. In particolare riferendoci ad ammassi affioranti lungo tratti stradali sono stati considerati due metodi classificativi, che ci hanno permesso di evidenziare sezioni a diverso rischio. Le metodologie utilizzate per la classificazione sono: - RHRS Pierson et al. 1990; - RHRS Russell et al. 2008. Ogni metodologia utilizza particolari tabelle che restituiscono punteggi la cui sommatoria cumulativa costituisce il Total Hazard Risk Score caratteristico di ogni sezione. Dopo aver discusso i risultati ottenuti ed aver analizzato i fattori determinanti per la diversa caratterizzazione del tratto stradale in sezioni a diverso rischio, è stata analizzata la compatibilità e le differenze tra i due metodi classificativi adottati.

En esta tesis se ha llevado a cabo el monitoreo de diferentes escarpes rocosos, que ha permitido la caracterización y la predicción de los desprendimientos de rocas. Esta caracterización y predicción han sido realizadas a partir de la comparación de nubes de puntos LiDAR obtenidos mediante un instrumento del tipo terrestre (ILRIS- 3D, Optech). La principal ventaja del uso de este tipo de instrumentos es la posibilidad de adquirir datos relativamente precisos (+/- 1 cm) a una distancia considerable (+/- 400 m) sin tener que alterar el comportamiento natural de la pared rocosa y sin que exista ningún riesgo por la instalación de instrumentos en el propio escarpe. En primer lugar se eligió un área de estudio piloto en la cual no existiera riesgo por caídas de rocas y poder de esta manera observar la evolución natural de las zonas inestables de la pared rocosa. Este hecho permitió el desarrollo de metodologías para la caracterización y predicción de los desprendimientos de rocas a partir de los datos LiDAR. La zona elegida fue el área de estudio piloto de Puigcercós, que consiste en el escarpe de coronación de un antiguo deslizamiento ocurrido en el año 1881. Dicho enclave ya estaba siendo monitoreado por el grupo RISKNAT desde el año 2007, y esta tesis supone la continuación del monitoreo y de las investigaciones que se estaban llevando a cabo. Las diferentes metodologías desarrolladas y aplicadas satisfactoriamente en el área de estudio piloto, fueron aplicadas posteriormente en un área con un alto riesgo por desprendimientos de rocas tanto para edificios como para vehículos y personas, la Montaña de Montserrat. En concreto se eligieron dos enclaves críticos, las paredes que se sitúan justo detrás del recinto del Monasterio de Montserrat, cuyo monitoreo comenzó en el año 2011, y las paredes de Degotalls, situadas por encima del aparcamiento de dicho monasterio, y cuyo monitoreo comenzó en el año 2007. El análisis de los datos LiDAR del escarpe de Puigcercós después de 2506 días de monitoreo arroja importantes resultados en el ámbito de la caracterización e inventario de los desprendimientos de rocas, permitiendo la obtención de un listado muy detallado de los eventos ocurridos. Este detallado inventario supone un gran avance para los análisis de la relación M-F de los desprendimientos. Los datos LiDAR también han mostrado resultados relevantes en el ámbito de la predicción de los desprendimientos de rocas de mayor magnitud. En este caso la detección y posterior análisis de la evolución de las deformaciones precursoras han sido claves para la predicción espacial y temporal de los eventos de mayor volumen. Por otra parte, se ha avanzado de manera importante en cuanto a la detección y seguimiento de los denominados desprendimientos precursores, que son otro tipo de indicador precursor de desprendimientos de gran magnitud y que necesitan ser investigados aún en mayor profundidad. En cuanto al monitoreo LiDAR de las mencionadas paredes de la Montaña de Montserrat, la aplicación de las metodologías desarrolladas en Puigcercós ha proporcionado resultados muy satisfactorios. El monitoreo ha permitido obtener un inventario de desprendimientos con un detalle sin precedentes en las paredes analizadas, y la continuación de esta investigación permitirá conocer con un mayor detalle el comportamiento geomorfológico de las paredes de conglomerados. Además, las metodologías aplicadas han permitido la detección de movimientos precursores en dos bloques inestables. El análisis de la evolución de estos desplazamientos en uno de los bloques ha demostrado que se encuentra en un estado crítico cercano al momento de la caída. En conclusión, todos los resultados obtenidos en esta tesis suponen un gran avance hacia la mejor caracterización de los desprendimientos de rocas, y hacia la posible implementación de un instrumento LiDAR Terrestre en un sistema de alerta temprana de desprendimientos.
In this thesis we have carried out the monitoring of different rock scarps that have allowed rockfall characterization and prediction. This characterization and prediction has been performed using the comparison of LiDAR point clouds obtained with a ground-based instrument (ILRIS-3D, Optech). The main advantage of this remote sensor is the possibility to acquire relatively accurate data (circa 1 cm) at a great distance (circa 400 m), without changing the natural behavior of the rock slope and without assuming any risk derived from the installation of instruments in the scarp. First, we chose a pilot study area without rockfall risk and which allowed us the observation of the natural evolution of instabilities. This lets the development of methodologies to characterize and predict rockfall events using the LiDAR datasets. The chosen place was the pilot study area of Puigcercos, which consists on the main scarp of an ancient landslide occurred in 1881. This rock face was already being monitored by the RISKNAT group since 2007, and this thesis involves the continuation of this monitoring and this research. The different methodologies developed and successfully applied in the pilot study area, were employed then in an area with a high rockfall risk for both buildings and vehicles and people, Montserrat Mountain. Specifically two critical sites were chosen, the cliffs located just behind Montserrat Monastery, whose monitoring started in 2011; and Degotalls rock face, located behind the parking of the Monastery, whose monitoring started in 2007. a very detailed rockfall list. This detailed inventory is a great improvement in the analysis of M-F relation of rockfalls. Also, the detection of pre-failure deformation and the analysis of its evolution have allowed a great improvement in the spatio-temporal prediction of high magnitude rockfalls. On the other hand, we have improved the detection and monitoring of precursory rockfalls, which is another kind of precursory indicator of high magnitude rockfalls that needs to be further investigated. Regarding the LiDAR monitoring of the Montserrat Mountain rock faces, the application of the processes developed in Puigcercós scarp has provided satisfactory results. This monitoring has allowed obtaining a rockfall inventory with an unprecedented level of detail. Therefore, the continuation of this research will allow improving our comprehension of the geomorphologic behavior of these conglomerate cliffs. Furthermore, the methodologies applied have allowed the detection of pre-failure deformation in two unstable blocks. The analysis of this pre-failure deformation in one of these instabilities has demonstrated its critical condition close to the rockfall. In conclusion, the results obtained in this thesis are a major contribution in rockfall characterization and prediction. These results also provide initial knowledges in order to implement a Terrestrial LiDAR instrument in an early warning system of rockfalls.

Il presente lavoro ha lo scopo di analizzare con il metodo Rockfall Hazard Rating System (Pierson et al, 1990) un tratto di strada lungo la SS612 nei comuni di Molina di Fiemme (Tn) e Anterivo (Bz) in tre zone distinte e valutarne il rischio rispetto ai fenomeni di crollo.

An inventory of unstable slopes along transportation corridors and performance modeling are important components of geotechnical asset management in Great Smoky Mountains National Park (GRSM). Hazards and risk were assessed for 285 unstable slopes along 151 miles of roadway. A multi-criteria model was created to select fourteen sites for two-dimensional probabilistic rockfall simulations and Acid Base Accounting (ABA) tests. Simulations indicate that rock material would likely enter the roadway at all fourteen sites. ABA test results indicate that influence of significant acid-producing potential is generally confined to slaty rocks of the Anakeesta Formation and graphitic schist of the Wehutty Formation. The research illustrates an approach for prioritizing areas for site-specific investigations towards the goal of improving safety in GRSM. These results can help park officials develop mitigation strategies for rockfall, using strategies such as widening ditches and encapsulating acidic rockfall material.

De nombreuses incertitudes liées aux mécanismes d'interaction entre les blocs rocheux et le versant naturel lors des chutes de blocs persistent ; la prévision de tels événements reste de ce fait encore incertaine. Néanmoins, les outils numériques et la puissance de calcul ne cessent d'évoluer. Si, auparavant, les calculs trajectographiques étaient restreints à des géométries simplifiées et à des mouvements balistiques en deux dimensions, il devient désormais possible d'y intégrer des raffinements tels que la forme complexe des blocs, des modèles numériques tridimensionnels de terrain d’une grande définition ou une prise en compte fine des mécanismes dissipatifs au niveau du point d'impact entre le bloc et le versant de propagation.L’objectif principal de la thèse est d’analyser, avec un code numérique discret en trois dimensions, l’influence des paramètres de forme et d’interaction sur la nature du rebond dans un contexte d’ingénierie. Nous présentons tout d’abord une méthodologie d'identification et d'étude de sensibilité des paramètres de contact, élaborée et validée à partir d’expérimentations de laboratoire. Cette méthodologie a été appliquée par la suite à deux expérimentations de chute de blocs menées sur sites réels à moyenne et à grande échelle.L’étude réalisée à moyenne échelle a permis de confronter le modèle numérique à des données obtenues lors d'une campagne expérimentale sur voies ferroviaires commanditée par la SNCF et menée en collaboration avec IRSTEA. Les analyses qui ont été réalisées ont porté sur les vitesses d’impact des blocs avec le ballast et les distances de propagation.L’étude menée à grande échelle s’appuie sur plusieurs séries de lâchés de blocs réalisées sur le site expérimental de la carrière d'Authume dans le cadre d’un Benchmark proposé dans le cadre du Projet National C2ROP. L’objectif principal du Benchmark est de tester et de comparer entre eux des logiciels trajectographiques, des codes de calculs numériques et les pratiques d’ingénierie pour en définir la pertinence et les domaines de validité. Dans le cadre de la thèse, ce travail a été conduit en plusieurs phases (à l’aveugle puis avec des données partielles mesurées lors de la campagne d'essais) et nous présentons l'évolution de ces analyses à l'issue de chacune des phases. L’étude a porté principalement sur les vitesses, les hauteurs et les énergies de passage des blocs en certains points du profil de propagation, ainsi que sur les positions d’arrêt des blocs. Une étude sur l'influence de la forme des blocs sur les distances de propagations est également présentée.Enfin, un Benchmark interne réalisé au sein de l'entreprise IMSRN montre l’importance, sur les analyses, de l'expertise de l'opérateur, et des conséquences de l'utilisation de différents outils trajectographiques (en 2D et en 3D). Ces travaux mettent en lumière les problématiques actuelles auxquelles sont souvent confrontés les bureaux d'études et les ingénieurs en charge des études de risques
Numerous uncertainties related to the machanical interaction between rock boulders and the natural slope during block falls persist; and the forecast of such events is therefore still uncertain. Nevertheless, digital tools and computing power are constantly evolving. Previously, trajectory calculations were restricted to simplified geometries and two-dimensional ballistic movements, but it is now possible to incorporate refinements such as the complex shape of the blocks, three-dimensional numerical models of terrain of large sizes, as well as a better accounting of the dissipative mechanisms at the point of impact between the block and the run-out slope.The main objective of this work is to analyze, with a discrete elements code in three dimensions, the influence of the shape and interaction parameters on the nature of the rebound in an engineering context. We first present a methodology for identifying and studying the sensitivity of contact parameters, developed and validated from laboratory experiments. This methodology was subsequently applied to two block fall experiments conducted on medium and large real-scale scenarios.The study conducted on a medium scale allowed the numerical model to be compared with data obtained during an experimental rockfall tests campaign commissioned by the SNCF and conducted in collaboration with IRSTEA in a railway. The analyzes that were carried out mainly focused on the impact velocities of the blocks with ballast and propagation distances.The large-scale study is based on a series of block releases performed at the experimental site (Authume quarry, France) as part of a Benchmark proposed inside the National Project C2ROP. The mainly goal of this Benchmark is to access and compare trajectory softwares, numerical computation codes and engineering practices to define their relevance and validity domains. As part of the thesis, this work was conducted in several phases (blind phase and then conducted taking in account partial data measured during the experimental tests) and we present the evolution of these analyzes at the end of each one of these phases. The study focused on the velocities, heights and energies of the blocks at certain points of the propagation profile, as well as on the stopping positions of the blocks. The influence of block shapes on run-out distances is also presented.Lastly, an internal Benchmark performed within the IMSRN company shows the importance, on the analyzes, of the expertise of the operator, and the consequences derived from the application of different trajectography tools (in 2D and in 3D). This work highlights the current issues that are often faced by engineering offices and engineers in charge of risk quantification

Great Smoky Mountains National Park (GRSM) received 12.5 million visitors in 2020. With a high traffic volume, it is imperative roadways remain open and free from obstruction. Annual unanticipated rockfall events in GRSM often obstruct traffic flow. Using the Unstable Slope Management Program for Federal Land Management Agencies (USMP for FLMA) protocols, this study analyzes high priority unstable rock slopes through 1) creation of an unstable slope geodatabase and 2) generation of a final rockfall risk model using Co-Kriging from a preliminary risk model and susceptibility model. A secondary goal of this study is to provide risk estimation for the three most traveled transportation corridors within GRSM, as well as investigate current rockfall hazard warning sign location to ultimately improve visitor safety with regards to rockfall hazards.

The study area, which will be open to tourism in Kusadasi (Aydin), has steep and high cliffs near the Aegean coast. In the area where some slidings and rockfall problems occurred in the past the geological hazards should be investigated and nature-friendly remedial measures should be taken. The aim of this study is to perform engineering geological studies to:(i) search geological hazards, (ii) reveal the slope stability problems, (iii) recommend nature-friendly solutions in order to prevent/minimize the hazards and (iv)compare the results obtained from 2-D and 3-D rockfall analyses. To accomplish these tasks, the geological survey was performed, the information about the discontinuities was collected by means of scanline surveys, the rock samples were collected, the in-situ and laboratory tests were carried out, the slope stability and rockfall analyses were performed for different slope conditions, remedial measures were offered for the problematical areas considering the data obtained and the results of 2-D and 3-D analysis were compared. Under the light of these studies, rock removal, drainage, greening (vegetation), filling the caverns, wall building and erosion prevention were offered as remedial measures. The comparison of the 2-D and 3-D rockfall analyses shows that the end points and bounce height values are different for each method. The differences between the 2-D and 3-D model originate from the slope geometry, the algorithm used in the software and the different input parameters. According to the field observations, the 2-D model is more realistic than 3-D model.

Rockfall represents a significant hazard not only in mountainous areas, but also alongside coastal routes, major transport infrastructures and quarry faces. One aspect of the rockfall phenomenon that still requires further investigations is the fragmentation of falling blocks upon impact. The changes in size, shape and energy of the falling blocks upon fragmentation and the variation in trajectory of the fragments can seriously affect the optimization design of the rockfall mitigation measures. The fragmentation of boulders during a rockfall event can lead to significant changes in the global run-out distances and the maximum kinetic energy to be accounted in the protection systems design. This thesis presents an experimental program conducted to investigate the fragmentation phenomenon under controlled conditions to provide some useful insights in terms of block survival probability upon dynamic impact, fragments distribution, post impact velocity and energy dissipation upon impact. The result of this thesis will focus on a detailed description of the fragmentation process and study several fragmentation mechanisms involved, reproducing many experimental observations of fragment shapes and impact energy, and significantly improve the understanding of the fragmentation process for impact fracture. Spheres shapes were chosen because of their simple body geometry and consequent impact and stress field symmetry. So, the description of materials, sample preparation and tests program conducted for 175 mortar spheres of different diameter built for the current research will be presented to evaluate the survival probability of homogeneous artificial rocks with a known compressive strength dropped from a certain height and to observe the fragmentation process upon impact with a known impacting energy.

Assessing long-term rock stability is an important aspect in the analysis of slopes, dam and bridge foundations, and other infrastructure. Rock behavior over tens to thousands of years must be anticipated when predicting the performance of, for example, an underground containment facility for nuclear waste. At such long time scales, the time dependence of rock failure, typically ignored in short time scale analyses, has a significant effect and must be included in the analysis. Since time-dependent rock behavior is thought to be caused by the subcritical growth of microcracks, a time-dependent analysis should incorporate a method of simulating subcritical crack growth. In this thesis, a rock bridge damage model was developed using the finite element program Abaqus to simulate subcritical crack growth for all three modes of crack tip displacement in three-dimensional rock masses. Since subcritical crack growth is not among the damage initiation and evolution criteria available in Abaqus, its effect was included in the model through the USDFLD user subroutine. Material properties for the damage model were obtained through laboratory fracture toughness testing of Escabrosa limestone from Kartchner Caverns. Tests included the grooved disk test for mode I, the punch-through shear with confining pressure test for mode II, and the circumferentially-notched cylindrical specimen test for mode III. The subcritical crack growth parameters n and A were calculated for all three modes using the constant stress-rate method. Fracture test results were compared with a previous study by Tae Young Ko at the University of Arizona, which tested Coconino sandstone and determined that the subcritical crack growth parameters were consistent among modes. This thesis expands upon Ko's work by adding the characterization of a second rock material in all three modes; results indicate that for Escabrosa limestone the subcritical crack growth parameters are not consistent among modes. Additionally, the Escabrosa limestone composing the caverns ranges from a more homogeneous, even-grained texture to a more heterogeneous texture consisting of coarse-grained veins and solution cavities set in a fine-grained matrix. To determine if the veined regions are more susceptible to fracturing and act as the nuclei of rock bridge failure, the fracture toughness tests were conducted separately for each texture. Results indicate that the more heterogeneous limestone has a higher fracture strength, fracture toughness, and subcritical crack growth index n than the more homogeneous limestone. This is in agreement with previous studies that determined that a more complex and heterogeneous microstructure produces a larger microcrack process zone and a more tortuous crack path, leading to higher fracture energies and larger values of n. Application of the rock bridge damage model to a simplified Kartchner cave room with a single roof block provided visualization of decreasing rock bridge size and produced time-to-failure estimates of 1,251 to 65,850 years. Multiple models were run to study the effect of (i) using material properties from each of the two textures identified in the Escabrosa limestone and (ii) varying the in-situ stress ratio, K. Both the value of K and the choice of Escabrosa texture had a large effect on the estimated time-to-failure, indicating that for future modeling of Kartchner accurate estimation of the in-situ stress ratio is as important as field identification of homogeneous vs. heterogeneous textures.