To see the other types of publications on this topic, follow the link: Geotechnical analyses.
Dissertations / Theses on the topic 'Geotechnical analyses'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Geotechnical analyses.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
RIBEIRO, ROMULO CASTELLO HENRIQUES. "APLICATIONS OF PROBABILITY AND STATISTICS IN GEOTECHNICAL ANALYSES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2008. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=12963@1.
Full textAbstract:
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO<br>Em análises geotécnicas, previsões de deformações ou de
fatores de segurança são desenvolvidas com base em métodos
determinísticos, que admitem como fixos e conhecidos os
parâmetros do solo ou da rocha. Entretanto, tais
previsões são afetadas por incertezas provenientes da
impossibilidade de reprodução das condições de campo em
laboratório, da perturbação do solo devida
à instalação de instrumentos, das ocorrências geomecânicas
não detectadas durante a campanha de sondagens, da
variabilidade inerente ao maciço, entre
outras. O estudo da influência dessas incertezas sobre os
cálculos determinísticos, com a possibilidade da
quantificação do risco de insucesso associado a um projeto
geotécnico, desenvolveu-se durante as últimas décadas com
base nas teorias de probabilidade e estatística. O presente
trabalho realiza uma revisão bibliográfica de conceitos
básicos de probabilidade e estatística, mostrando alguns
avanços da aplicação desses conceitos na engenharia
geotécnica. Visando apresentar formas de estimarem-se
probabilidades de recalque inadmissível ou de ruptura são
realizadas análises para os seguintes casos: recalques de
argila mole solicitada por aterro e de fundações
superficiais em areia, estabilidade de fundação superficial
em solo residual e de fundação profunda em solo sedimentar,
deslizamento de um muro de arrimo e estabilidade de um
talude. Com o objetivo de inferir acerca dos
fatores que influenciam as estimativas probabilísticas,
para cada caso são realizadas comparações entre resultados
obtidos com base em diferentes métodos probabilísticos e/ou
determinísticos.<br>In geotechnical analyses, forecasts of safety factors or
deformations are developed on the basis of deterministics
methods, that admit as fixed and known
the parameters of the soil or the rock. However, such
forecasts are affected by uncertainties proceeding from the
reproduction impossibility of the field
conditions in laboratory, of the disturbance of the soil
under installation of instruments, of the not detected
geomechanics occurrences during the soundings
campaign, of the inherent variability to the soil, among
others. The study of the influence of these uncertainties
on the deterministics calculations, with the
possibility of the risk quantification of failure
associated with a getechnical project, developed during the
last decades on the basis in theories of probability
and statistics. The present work make a bibliographical
revision of basic concepts of probability and statistics,
showing some advances of the application of these
concepts in geotechnical engineering. With the objective to
show forms of computing probabilities of rupture or of
inadmissible settlement are make analyses for the following
cases: settlement of fill on soft clay, settlement of
superficial foundations in sand, stability of superficial
foundation in residual soil, stability of deep foundation
in sand, stability of retaining wall and dam slope
stability. With the objective to verify the factors that
influence the probabilist estimates, for each case is make
comparisons between results given of different
probabilist and/or deterministics methods.
2
Ho, David Kar Hung. "Analyses of geotechnical construction by the finite element method." Thesis, University of Manchester, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277388.
Full text
3
McCombie, Paul F. "Some developments of limit equilibrium analyses in geotechnical engineering." Thesis, University of Bath, 2008. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501625.
Full textAbstract:
Four journal papers have been selected from the candidate's published research output, to represent his work in developing analytical methods for use in geotechnical engineering design and analysis. Two of the papers contribute to significant advances in the understanding of the behaviour of dry-stone retaining walls, which will lead to greater confidence in the assessment of existing walls and the design of new walls. The other two papers develop optimisation and analysis routines with the aim of supporting the assessment of slope stability, and the design of new cut and built slopes and stabilisation works.
4
El-Hamalawi, Ashraf Abdul-Rahman. "Adaptive refinement of finite element meshes for geotechnical analyses." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627406.
Full text
5
Kim, Jong Hee. "Improvement of geotechnical site investigations via statistical analyses and simulation." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41218.
Full textAbstract:
The purpose of this study is to improve site investigation in geotechnical engineering via the evaluation and development of statistical approaches for characterizing the spatial variability of soil properties and the development of site investigation simulation software for educational use.
This study consists of four components: statistical characteristics, data measurement, simulation, and educational training. Statistical measures of spatial variability of soil properties were examined for three different geographical areas where soil formation processes differ to assess the influence on the spatial variability of soils. Statistical measures of spatial variability were also calculated for a case history where blasting was used as a method of soil improvement to evaluate the effects of man-made changes to soil structure.
The concept of spatial aliasing was employed to estimate the maximum allowable sampling interval for field data as a function of the spatial correlation properties. Once a maximum statistically allowable sampling interval is determined for a specific soil property, the minimum statistically required number of soundings / borings is calculated to perform an economical site investigation at a specific site.
A simple and efficient simulation technique was proposed to generate correlated, multi-dimensional simulations of soil properties. Based on limited data, the proposed simulation technique generated accurate and correlated simulations of soil properties that are consistent with the observed or proposed correlation structures of soil properties.
Lastly, a geotechnical site investigation simulation program with a wide variety of in situ and laboratory tests was developed to allow students to plan and perform a comprehensive site investigation program. The simulation generates an input file based partly on the statistical characteristics of the spatial variability of soil properties analyzed in this study and partly on traditional values. Spatial variability in soil properties is modeled via correlated random fields, interpolation, and a decomposition method to yield realistic geotechnical data. Via the simulation, students are able to obtain experience and judgment in an essential component of geotechnical engineering practice.
The four components of this research (statistical characteristics, data measurement, simulation, and educational training) focus on the improvement of site investigation performance in geotechnical engineering, thereby improving reliability analysis in geotechnical practice.
6
Karparov, Krassimir Nikolov. "Slope stability analyses in complex geotechnical conditions thrust failure mechanisms /." Pretoria : [s.n.], 2003. http://upetd.up.ac.za/thesis/available/etd-03092007-153601.
Full text
7
Lindberg, Niclas. "Three-dimensional effects in slope stability for shallow excavations : Analyses with the finite element program PLAXIS." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-79961.
Full textAbstract:
The purpose with this study was to investigate the impact of three-dimensional effects in slope stability for three-dimensional excavations and slopes with cohesive soils and compare the results with the method provided by the Swedish commission of slope stability in 1995 regarding three-dimensional effects. Both the factor of safety and the shape of the slip surface was compared between the methods but also the results from their equivalent two-dimensional geometry. The investigation was performed with models created in the finite element software PLAXIS 3D and the limit equilibrium software GeoStudio SLOPE/W. Three-dimensional excavations with varying slope angles, external loads and slope lengths were tested for three different geometry groups in PLAXIS 3D. The equivalent two-dimensional geometries were modeled with SLOPE/W and recalculated with the three-dimensional effect method provided by the Swedish commission of slope stability. The results show that the methods match well for slopes with inclinations 1:2 and 1:1 when an external load is present on the slope edge, and the factor of safety is greater and not close to 1,0. For an excavation with vertical walls or when no external load is present, the methods match poorly. The results also show that for a long and unloaded slope, the factor of safety approaches the value obtained from a simplified two-dimensional analysis. The results imply that the recommendations from the Swedish commission of slope stabilityare reliable for simple calculations of standard cohesive slopes. Keywords: Slope stability; 3D-effects; FEM
8
Clark-Mostert, Vennessa. "Geotechnical and risk analyses for the positioning of shafts at the Wesizwe Platinum project." Diss., University of Pretoria, 2011. http://hdl.handle.net/2263/79216.
Full textAbstract:
The Wesizwe main and ventilation shaft positions are sited within an almost square block formed by four faults. The shaft positions were not sited within the centre of gravity of the Wesizwe lease area. This is due to factors related to the local community and various environmental issues. It was decided to position the shaft in the current block as geological and rock engineering confidence was high in regard to the structures within the area, and the shaft position was falling within the allowable distance radius from the nearby community and river boundary.
A seismic survey, conducted on the area, indicated a near vertical fault. The fault, which has a 30m throw, occurs approximately 50m north of the position at which the main shaft was site. It was suggested that this fault, which was a reinterpretation of the northern boundary fault, would have a negative effect on the rock mass behaviour in the shafts.
Previously it was noted that the shaft level breakaways and geotechnical borehole information do not correlate. A 20m vertical discrepancy was observed between the planned Merensky breakaway and the Merensky position indicated by drilling. The logical interpretation was that this was due to faulting and a note was sent out to make the project team aware of this 20m discrepancy. This was again brought to the team’s attention upon the release of the seismic study interpretation indicating a 30m fault in this area.
Geotechnical logging had already been done on the diamond drill holes sunk at the positions indicated for the Wesizwe Main and Vent Shafts. The rock mass ratings indicated that these positions were favourable and that the rock mass of the shafts can be referred to as “Good Rock”. To determine what the geotechnical character of the fault was, four boreholes (WF01, WF049, WF059 and WF090) were geotechnically logged at the predicted depths of the fault intersection.
Two zones carrying less competent ground were identified near the fault intersection positions as was indicated by the seismic interpretation. By combining the zones into one area of less competent ground it was found that the affected area does not exceed a vertical influence of 58m, and has a minimum vertical influence of 25m. The rock mass in these affected areas are overall rated as “poor rock” to “exceptionally poor rock”. The rock quality designation (RQD) ratings for the affected area fall between 36 to 52 %.
A decision needed to be reached as to whether the shafts would be developed at the positions indicated, or whether a new area needed to be selected for the main and ventilation shaft positions. This decision was reached by combining all available information and weighing the risks related to the options. From this study, a general approach to shaft positioning for platinum projects was formulated.<br>Dissertation (MSc)--University of Pretoria, 2011.<br>Geology<br>MSc<br>Unrestricted
9
Clark-Mostert, Vannessa. "Geotechnical and risk analyses for the positioning of shafts at the Wesizwe Platinum project." Diss., University of Pretoria, 2011. http://hdl.handle.net/2263/31499.
Full textAbstract:
The Wesizwe main and ventilation shaft positions are sited within an almost square block formed by four faults. The shaft positions were not sited within the centre of gravity of the Wesizwe lease area. This is due to factors related to the local community and various environmental issues. It was decided to position the shaft in the current block as geological and rock engineering confidence was high in regard to the structures within the area, and the shaft position was falling within the allowable distance radius from the nearby community and river boundary.
A seismic survey, conducted on the area, indicated a near vertical fault. The fault, which has a 30m throw, occurs approximately 50m north of the position at which the main shaft was site. It was suggested that this fault, which was a reinterpretation of the northern boundary fault, would have a negative effect on the rock mass behaviour in the shafts.
Previously it was noted that the shaft level breakaways and geotechnical borehole information do not correlate. A 20m vertical discrepancy was observed between the planned Merensky breakaway and the Merensky position indicated by drilling. The logical interpretation was that this was due to faulting and a note was sent out to make the project team aware of this 20m discrepancy. This was again brought to the team’s attention upon the release of the seismic study interpretation indicating a 30m fault in this area.
Geotechnical logging had already been done on the diamond drill holes sunk at the positions indicated for the Wesizwe Main and Vent Shafts. The rock mass ratings indicated that these positions were favourable and that the rock mass of the shafts can be referred to as “Good Rock”. To determine what the geotechnical character of the fault was, four boreholes (WF01, WF049, WF059 and WF090) were geotechnically logged at the predicted depths of the fault intersection.
Two zones carrying less competent ground were identified near the fault intersection positions as was indicated by the seismic interpretation. By combining the zones into one area of less competent ground it was found that the affected area does not exceed a vertical influence of 58m, and has a minimum vertical influence of 25m. The rock mass in these affected areas are overall rated as “poor rock” to “exceptionally poor rock”. The rock quality designation (RQD) ratings for the affected area fall between 36 to 52 %.
A decision needed to be reached as to whether the shafts would be developed at the positions indicated, or whether a new area needed to be selected for the main and ventilation shaft positions. This decision was reached by combining all available information and weighing the risks related to the options. From this study, a general approach to shaft positioning for platinum projects was formulated.<br>Dissertation (MSc)--University of Pretoria, 2011.<br>Geology<br>MSc<br>Unrestricted
10
Yang, Zhaohui. "Development of geotechnical capabilities into OpenSees platform and their applications in soil-foundation-structure interaction analyses /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2002. http://uclibs.org/PID/11984.
Full text
11
Scherer, Rebecca Elizabeth. "Settlement Analyses of Grade Supported Tanks Constructed with the Use of Prefabricated Wick Drains and an Earth Preload." ScholarWorks@UNO, 2011. http://scholarworks.uno.edu/td/1345.
Full textAbstract:
In the design of tank foundations several design techniques are considered. This study focuses on grade supported tanks constructed under an extensive preload and instrumentation program. Settlement estimation methods were performed and compared to field instrumentation data taken at the project sites. Three project sites were selected for this study. The geotechnical investigations were performed by Eustis Engineering Services, L.L.C. and included both undisturbed soil borings and cone penetrometer tests. Conclusions were made about the accuracy of the calculations and how assumptions affect the settlement computation results.
12
Yederulh, Hulumtaye Kefyalew. "Settlement calculation for lime/cement column improved clay : Analytical and numerical analyses related to a case study." Thesis, KTH, Jord- och bergmekanik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-221724.
Full textAbstract:
The dry deep mixing method is widely used to improve a soft clay soil to increase the shear strength as well as to reduce the time for consolidation. It is a mechanical mixing process that makes parts of the soil stiffer than its original strength. It is mainly applicable to soft clay or peat soil. In this master thesis, the objective was set to perform a comparative analysis on the prediction of the settlements of a clay soil improved by lime/cement columns (LCC). The theoretical settlement predictions were made using two analytical and numerical modeling. A case study was carried out on a part of Stockholm bypass project where LCC was applied to improve soft clay for a foundation of a concrete trough. Field measurements of the vertical deformation of the improved soil were performed using settlement plates to compare the analytical and numerical results. The first analytical method was performed based on the recommendation of TK Geo 13 (2013) while the second method was performed based on the concept of a composite ground. In the case of the numerical method, FEA was performed using 2D plane strain model in Plaxis simulation. The performance of the geometry and combined matching models were investigated to convert the axisymmetric to plane strain model. The variation in stiffness of the columns were taken into consideration by applying two stiffness values 30 and 33 MPa for the upper and lower half of the column respectively. A preload of 58 kPa was applied on the improved clay soil to simulate the time-dependent consolidation settlement due to the stress addition. A comparison was carried out between the results obtained from the analysis and a field measurement. The two analytical methods produced a better agreement with the field measurement regarding long-term consolidation settlement and a reasonable agreement concerning the rate of consolidation. The numerical analysis showed a good agreement with the benchmark concerning both the long-term consolidation settlement as well as the rate of consolidation. The geometry matching model gave a reasonable result regarding correctness of the result compared with the combined matching. Based on the results obtained in this study, the numerical methods had a better agreement with the measurements.<br>Jordförstärkning med kalkcementpelare är en vanlig metod för förstärkning av lösa jordar genom ökning av den blandade jordens hållfasthet samt minskning av konsolideringstiden. Metoden är en mekanisk process som ökar jordens styvhet och är främst tillämpbar i lös leror men även organiska jordar. Detta examensarbete har syftat till att jämföra sättningsberäkningar i lera som är förstärk med KC-pelare. De teoretiska beräkningarna har utförts genom två analytiska modeller samt numerisk modellering. En fallstudie har utförts på del av Förbifart Stockholm där jordförstärkning av lös lera med KC-pelare har använts inför grundläggning av ett betongtråg. Resultat från fältmätningar av installerade markpeglar har jämförts med resultat från de teoretiska sättningsberäkningarna. Den första beräkningsmetoden utfördes i enlighet med rekommendationer från TK Geo 13 (2013) och den andra metoden är baserad på principer för kompositjordar. Den numeriska beräkningen har utgjorts av FEM-modellering i 2D i programmet Plaxis. För att anpassa en plan-töjningsmodell till en axialsymmetrisk modell har inverkan av geometrin samt kombinerad anpassning av modell studerats. Hänsyn har tagits till KC-pelarnas styvhet genom att använda två olika värden (30 resp. 33 MPa) för KC-pelarnas övre respektive undre del. En överlast om 58 kPa applicerades på KC-pelarförstärkt området för att påskynda den tidsberoende konsolideringssättningarnas förlopp som orsakas av överlastens tillskottspänningar. Baserat på resultat från uppmätta sättningar jämfört med beräkningar, har följande slutsatser dragits. Jämförelser mellan resultaten har visat på en rimlig överrensstämmelse mellan de två analytiska metoderna och utförda fältmätningar avseende långtids konsolideringssättningar. Den numeriska beräkningen har visat en god överensstämmelse med fältmätningar med hänsyn till både konsolideringssättningar och konsolideringsgraden. Den geometriskt anpassade modellen visade ett rimligare resultat i förhållande till den kombinerade anpassade modellen. Sammanfattningsvis bedöms det att den numeriska modelleringen stämmer bättre överens med resultaten från uppmätta sättningar i förhållande till analytiska beräkningar.
13
Zardari, Muhammad Auchar. "Numerical analyses of stability of a gradually raised tailings dam." Doctoral thesis, Luleå tekniska universitet, Geoteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26598.
Full textAbstract:
Numerical analyses are presented in this thesis to address potential stability problems that may occur during gradual raisings and under seismic loading conditions of Aitik tailings dam in northern Sweden. The dam is mainly raised using upstream construction method. It is planned to raise the dam gradually in several stages. Two dam parts were studied. The first dam part is a straight dam portion, and the second dam part is a corner. The main concerns associated with future raisings of the straight dam part were: (i) the stability of the dam could be affected by an increase in excess pore pressures during sequential raisings, (ii) how to gradually strengthen the dam by using rockfill berms as supports in such a way that required slope stability can be achieved with a minimum volume of rockfill berms, and (iii) if the dam is subjected to seismic loading, whether or not an increase in excess pore pressures could lead to extensive liquefaction which may cause a failure. The problems related to the dam corner were that tension zones and/or low compression zones could develop because of the horizontal pressure of the stored tailings on the inside of the curvature of the dam corner.Numerical analyses were conducted on both the dam parts using finite element method. Two dimensional (2D) plane strain finite element model was utilized to analyse the straight dam. The dam corner was analysed with both the three dimensional (3D) finite element model, and the 2D axisymmetric finite element model. Coupled deformation and consolidation analyses, and slope stability analyses were performed on both the dam parts to simulate gradual raisings, and to compute safety factors. In addition to this, dynamic analyses were carried out on the straight dam part to evaluate the potential for liquefaction, and seismic stability of the dam. The seismic behaviour of the dam was analysed for two cases: (i) a normal case (earthquake of 3.6 Swedish local magnitude), and (ii) an extreme case (earthquake of 5.8 moment magnitude).The results of the straight dam part, with only previously existing rockfill berms, indicate that stability of the dam was reduced due to an increase in excess pore pressures during raisings. Rockfill berms were utilized as supports to raise the dam with enough safety. An optimization technique was utilized to minimize the volume of rockfill berms. This technique could result in significant saving of cost of rockfill berms.The results of the dam corner show that tension zones and/or low compression zones were located on the surface of the dam corner, mainly above the phreatic level. It is interpreted that there is no risk of internal erosion through the embankments because no seepage path occurs above the phreatic level, and a filter zone exists along the slope of the dam. It is suggested to gradually strengthen the dam corner with rockfill berms. The results of the 2D axisymmetric analyses of the dam corner were in a fairly good agreement with those of the 3D analyses. This implies that the 2D axisymmetric analyses are valid for this dam corner. This is an important finding as 2D axisymmetric analyses require much less computational time compared to 3D analyses.The results of the dynamic analyses performed on the straight dam (including additional rockfill berms) suggest that, for the extreme case, liquefaction could occur in a limited zone that is located below the surface near the embankments. For both the normal and the extreme case, (i) seismically induced displacements seem to be tolerable, and (ii) the post seismic stability of the dam is considered to be sufficient.The findings of this study have been practically applied to the Aitik tailings dam. In general, the modelling procedure and the optimization technique to minimize volume of rockfill berms, presented in this study, could be applied to other tailings dams.<br>Godkänd; 2013; 20130513 (muhauc); Tillkännagivande disputation 2013-05-20 Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Muhammad Auchar Zardari Ämne: Geoteknik/Soil Mechanics and Foundation Engineering Avhandling: Numerical Analyses of Stability of a Gradually Raised Tailings Dam Opponent: Professor Daichao Sheng, School of Engineering, The University of Newcastle, New South Wales, Australia Ordförande: Professor Sven Knutsson, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Torsdag den 13 juni 2013, kl 10.00 Plats: F1031, Luleå tekniska universitet
14
Chandarana, Upasna Piyush, and Upasna Piyush Chandarana. "Optimizing Geotechnical Risk Management Analysis." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/625550.
Full textAbstract:
Mines have an inherent risk of geotechnical failure in both rock excavations and tailings storage facilities. Geotechnical failure occurs when there is a combination of exceptionally large forces acting on a structure and/or low material strength resulting in the structure not withstanding a designed service load. The excavation of rocks can cause unintended rock mass movements. If the movement is monitored promptly, accidents, loss of ore reserves and equipment, loss of lives, and closure of the mine can be prevented. Mining companies routinely use deformation monitoring to manage the geotechnical risk associated with the mining process. The aim of this dissertation is to review the geotechnical risk management process to optimize the geotechnical risk management analysis. In order to perform a proper analysis of slope instability, understanding the importance as well as the limitations of any monitoring system is crucial. Due to the potential threat associated with slope stability, it has become the top priority in all risk management programs to predict the time of slope failure. Datasets from monitoring systems are used to perform slope failure analysis. Innovations in slope monitoring equipment in the recent years have made it possible to scan a broad rock face in a short period with sub-millimetric accuracy. Instruments like Slope Stability Radars (SSR) provide the quantitative data that is commonly used to perform risk management analysis. However, it is challenging to find a method that can provide an accurate time of failure predictions. Many studies in the recent past have attempted to predict the time of slope failure using the Inverse Velocity (IV) method, and to analyze the probability of a failure with the fuzzy neural networks. Various method investigated in this dissertation include: Minimum Inverse Velocity (MIV), Maximum Velocity (MV), Log Velocity (LV), Log Inverse Velocity (LIV), Spline Regression (SR) and Machine Learning (ML). Based on the results of these studies, the ML method has the highest rate of success in predicting the time of slope failures. The predictions provided by the ML showed ~86% improvement in the results in comparison to the traditional IV method and ~72% improvement when compared with the MIV method. The MIV method also performed well with ~75% improvement in the results in comparison to the traditional IV method. Overall, both the new proposed methods, ML and MIV, outperformed the traditional inverse velocity technique used for predicting slope failure.
15
Faria, P. de D. "Shakedown analysis in geotechnical engineering." Thesis, Swansea University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636956.
Full textAbstract:
Many problems in geotechnology are concerned with the response of earth materials to cyclic loads. These loads are either generated by forces of nature such as sea waves, currents, winds, and earthquakes or as a consequence of engineering operations such as blasting, pile driving and rotating machines. For most design purposes related to static loads it is logical to use as a design basis either the elastic range where no plastic deformation occurs or the plastic range, in which large plastic deformation can occur. However, when cyclic loading is involved few design methods are available since a pattern for the response of the body to cyclic loads is not well known. When a body is subjected to cyclic loading some modes of adaptation or non adaptation can occur as a response to the loads such as elastic shakedown, alternating plasticity and ratchetting. Despite its extensive use in structural problems very few applications of the shakedown approach to soil masses can be found in literature. Therefore the present work aims to extend the elastic shakedown concepts to geotechnical problems. Initially the shakedown concepts are introduced, its theorems and their importance for geomechanical problems are highlighted. Later the use of Melan's static shakedown theorem for the present study is shown. Shakedown analyses of plane stress and plane strain problems are presented. In this study the shakedown formulation is based on the concept of a residual stress field obtained by means of a numerical formulation using a visco-plastic algorithm. Two numerical codes linked with a mesh generator were implemented as tools for the treatment of the shakedown problems. Numerical examples and applications are shown to illustrate the usefulness of the present approach.
16
Santos, Stephane do Nascimento. "Simulação numérica de dutos enterrados, submetidos à perda de apoio e elevação localizada." Universidade do Estado do Rio de Janeiro, 2014. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=9092.
Full textAbstract:
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>Os recentes desastres ocorridos no país, como o rompimento da adutora em
Campo Grande e os desastres relacionados às enchentes urbanas, mostram a
necessidade de desenvolvimento de pesquisas científicas que auxiliem na
compreensão e no dimensionamento das estruturas projetadas para atender a
demanda da população. Os métodos analíticos e experimentais mais utilizados
possuem algumas limitações de ordem teórica ou prática. Por outro lado, os
métodos numéricos, capazes de simular etapas construtivas e envolver materiais
com diferentes modelos constitutivos numa mesma análise, buscam atender às
necessidades práticas dos projetos de geotecnia e, ao mesmo tempo,
complementam os modelos analíticos e experimentais. Nesse trabalho foram
realizadas comparações entre resultados obtidos em ensaios experimentais e
resultados extraídos do modelo computacional, buscando aumentar a compreensão
sobre a interação solo-estrutura em relação à distribuição de tensões mobilizadas e
aos deslocamentos e deformações provocados. A simulação numérica foi feita com
a utilização do PLAXIS/3D, software de análise geotécnica baseado no método dos
elementos finitos. Os ensaios foram confeccionados na Escola de Engenharia de
São Carlos/USP por Costa (2005) e envolveram dutos enterrados submetidos à
perda de apoio ou elevação localizada. O estudo experimental foi realizado através
de modelos físicos compostos por um maciço de areia pura, contendo um tubo
repousando sobre um alçapão no centro do vão. Os modelos físicos foram
equipados com instrumental capaz de medir as deflexões e as deformações
específicas ao longo do duto, além das tensões totais no maciço de solo circundante
e na base do equipamento.<br>Recent disasters that occurred in this country, like the failure of a pipeline in
Campo Grande and others disasters related to urban flooding, show us the need for
developing scientific researches that help us to understand the behavior of these
structures and to design them to serve the population. Analytical and experimental
methods have some theoretical and practical limitations. On the other hand,
numerical methods are capable to simulate staged constructions and to analyze
together materials with different constitutive models, supplying practical necessities
of geotechnical projects and complementing analytical and experimental models. In
this dissertation comparisons between experimental results and numerical results
have been made, trying to increase the comprehension about the interaction of soil
and pipe with respect to mobilized stress distribution, displacements and strains. The
numerical modeling was performed on PLAXIS 3D software, based on Finit Elements
Method. The experimental test was made by Costa (2005) at São Carlos Engineering
School/USP and involved buried pipes undergoing loss of support or elevation in a
localized region along its length. Tests have been performed with physical models
comprising dry and pure dry sand and a tube resting on a rigid trapdoor base located
at the center of its length. The models were equipped with devices for measuring
deflections and strains in the pipe, and total stresses in soil mass and in the lower
boundary of the model.
17
Rockaway, Thomas D. "Spatial assessment of earthquake induced geotechnical hazards." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/20038.
Full text
18
DYMINSKI, ANDREA SELL. "ANALYSIS OF GEOTECHNICAL PROBLEMS WITH NEURAL NETWORKS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2000. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=2001@1.
Full textAbstract:
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR<br>Nos últimos anos, a aplicação da técnica de redes neurais
tem sido difundida em diversas áreas do conhecimento,
inclusive na engenharia civil. Em meados da década de 90,
iniciaram-se no Brasil estudos no sentido de avaliar a
eficiência desta técnica numérica na modelagem do
comportamento de solos e na análise de problemas envolvendo
engenharia geotécnica. Este trabalho é resultado de parte
destes estudos, onde algumas das potencialidades do uso das
redes neurais em geotecnia podem ser observadas. São
apresentadas três aplicações diferentes de redes neurais
feedforward em geotecnia, tendo sido treinadas com o
algoritmo LM (Levenberg-Marquardt). A primeira aplicação
diz respeito à simulação de resultados de provas de carga
dinâmica, analisadas pelo método CAPWAP, através de redes
neurais, sendo assim viabilizada a realização de uma pré-
análise do comportamento da estaca ainda em campo, o que
geralmente não acontece quando se trata da análise CAPWAP
tradicional. A segunda aplicação relaciona-se com a análise
do comportamento mecânico de dois tipos de solo bastante
diferentes entre si: a areia de Ipanema e o solo residual
gnáissico do Rio de Janeiro. Para tal, foram utilizados
resultados de ensaios de cisalhamento direto, submersos e
não submersos, e ensaios de compressão triaxial, drenados e
não drenados. A terceira aplicação refere-se à simulação
das características do subsolo do sítio da Usina Nuclear
Angra 2, localizada no litoral do estado do Rio de Janeiro.
As informações disponíveis eram advindas de boletins de
sondagens do tipo SPT. Foram realizadas simulações
envolvendo a disposição das camadas dos diferentes tipos de
solo que poderiam existir no local, o nível de água
subterrâneo, a resistência à penetração do solo e a
topografia do terreno. Em todos os casos foram obtidos
resultados bastante satisfatórios. Portanto, conclui-se que
a técnica das redes neurais apresenta grande viabilidade na
resolução de problemas geotécnicos de diferentes
características, muitas vezes se mostrando tanto ou mais
eficiente que as técnicas numéricas tradicionais.<br>During the last years, neural networks applications have
been disseminated in many knowledge areas, including civil
engineering. In the middle 90`s, a research work had been
started in Brazil, in order to investigate the efficiency
of neural networks in the analysis of soil behavior and
problems involving geotechnical engineering. This thesis is
the result of part of these studies, where some
potentialities of neural networks technique are presented.
Three different feedforward NNs applications in
geotechnical engineering are presented. Levenberg-
Marquardt algorithm was used for training. The first
application is the simulation of results of dynamic pile
tests, obtained from CAPWAP analysis, showing that it is
possible to do a field pre-analysis of the pile behavior,
which is still unpracticable when the traditional CAPWAP
method is used. The second application is related to the
study of two different soils behavior:sand from Ipanema and
residual gnaissic soil from Rio de Janeiro. Results of
submerged and non submerged direct shear tests and drained
and undrained triaxial compression tests were
used. The third application involves the simulation of
subsoil characteristics of Angra 2 Nuclear Power Plant
site. The available information came from SPT bulletins.
Simulations involving several types of soil layers spatial
distribution, water level position, penetration strength of
soils and local topography were performed. The obtained
results were very satisfactory. It can be concluded that
the neural networks technique presents great applicability
in resolution of geotechnical problems with different
characteristics, showing an efficiency as good or even
better than other traditional numerical techniques.<br>En los últimos anos, la aplicación de técnicas de redes
neurales se ha difundido en diversas áreas del conocimento,
incluso en la ingeniería civil. A mediados de la década de
90, se iniciaran en Brasil estudios para evaluar la
eficiencia de esta técnica numérica em modelos de
comportamiento de suelos y en el análisis de problemas de
ingeniería geotécnica. Este trabajo es el resultado de
parte de estos estudios, donde pueden ser obseravdas
algunas de las potencialidades del uso de las redes
neurales en geotecnia. Se presentan tres aplicaciones
diferentes de redes neurales fedforward en geotecnia,
entrenadas con el algoritmo LM (Levenberg Marquardt). La
primera aplicación se refiere a la simulación de resultados
de pruebas de carga dinámica, analizadas por el método
CAPWAP, a través de redes neurales, realizando un pré
análisis del comportamiento de la estaca en campo, lo que
generalmente no sucede cuando se trata del análisis CAPWAP
tradicional. La segunda aplicación se relaciona con el
análisis del comportamiento mecánico de dos tipos de suelo
bastante diferentes entre sí: la arena de Ipanema y el
suelo residual gnáisico de Rio de Janeiro. Para esto, se
uilizaron resultados de ensayos de cisallamiento directo,
submersos y no submersos, y ensayos de compresión triaxial,
drenados y no drenados. La tercera aplicación se refiere a
la simulación de las características del subsuelo del sitio
de la Planta Nuclear Angra 2, localizada en el litoral del
estado del Rio de Janeiro. Las informaciones disponibles
provenian de boletines del tipo SPT. Se realizaron
simulaciones que involucraban la disposición de los
diferentes tipos de suelo que podrían existir en el local,
el nível de agua subterránea, la resistencia a la
penetración del suelo y la topografia del terreno. En todos
los casos fueron obtenidos resultados bastante
satisfactorios. Por lo tanto, se concluye que la técnica de
redes neurales presenta gran viabilidad en la resolución de
problemas geotécnicos de diferentes características, muchas
veces mostrándose tanto o más eficiente que las técnicas
numéricas tradicionales.
19
Rabaiotti, Carlo. "Inverse analysis in road geotechnics /." Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=18135.
Full text
20
Hamade, Tarek. "Geotechnical design of tailings dams - a stochastic analysis approach." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=116869.
Full textAbstract:
Mine tailings dams are geotechnical structures that are designed to provide adequate and safe storage of tailings materials both during and after the end of mine life. The design of tailings dams is currently based on limit equilibrium methods (LEM) which are used to calculate slope stability safety factors under various operational loads. The minimum safety factor obtained from these analyses is retained to be the design safety factor. LEM's however suffer from a number of shortcomings most notably the lack of information on dam deformation and the interaction between effective stress and pore pressure. For this, advanced numerical modeling techniques accounting for the hydro-mechanical coupling occurring in the dam structure have been developed. These models provide much greater insight into the geotechnical behavior of the tailings dam. However, both LEM and numerical modeling approaches are deterministic in nature; thus, they do not take into consideration the inherent uncertainty of the construction material properties – a fact that is well known to the geotechnical engineer, yet, needs to be addressed.In this thesis, stochastic analysis approaches such as the Monte Carlo (MC) method are adopted to investigate the effect of the inherent uncertainty in material properties on the design factor of safety. Both LEM and coupled hydro-mechanical numerical models are first developed and the results for deterministic models are compiled. These are then compared with the result obtained from stochastic analyses. A case study of a new water retention tailings dam project design with well documented geotechnical data is adopted throughout the thesis study. First the LEM analysis was pursued followed by a sensitivity analysis to determine the most influential parameters on the design safety factor. Next, a fully coupled hydro-mechanical model was developed with FLAC2D in which the construction sequence was simulated in seven stages. The factor of safety (FOS) was calculated at the end of every stage using the Strength Reduction Technique (SRT). Following that, the Point Estimate Method (PEM) was then used to obtain the probability of unsatisfactory performance by considering the dam's core angle of friction, cohesion and permeability as stochastic variables. The coefficient of variation for the material properties was varied and its consequence on the probability was recorded. Next, the MC method was adopted to calculate the tailings dam's probability of unsatisfactory performance as well as its reliability. The effect of changing the probability density function (PDF) of the stochastic input parameter on the output reliability was further analyzed. Furthermore, the effect of randomness at the local level was studied using the Random Monte-Carlo (RMC) method and compared to the output of the MC method.Finally, the effect of the coefficient of correlation between the dam's core angle of friction and its cohesion on the impoundment's reliability was analyzed. This was followed by an advanced stochastic analysis using the MC method that included a third stochastic variable, the dam's core permeability. The incorporation of both mechanical and hydraulic parameters as stochastic variables lowered the impoundment's reliability; thus, highlighting the power and novelty in the hydro-mechanical stochastic analysis hybrid approach. The results of all analyses are presented in the thesis along with the findings in the conclusion.<br>Les digues des résidus miniers sont des ouvrages géotechniques conçus pour offrir un stockage adéquat et sécuritaire des résidus et ce pendant et après la fin de la vie de la mine. La conception des digues à résidus est actuellement basée sur les méthodes d'équilibre limite (LEM) qui sont utilisés pour calculer les facteurs de sécurité de la stabilité des pentes sous diverses charges opérationnelles. Le facteur de sécurité minimal obtenu à partir de ces analyses est considéré comme facteur de sécurité de conception. Ils sont présentement utilisés dans la conception géotechnique. Cependant, LEM a des lacunes notamment le manque d'information sur la déformation d'une digue et de l'interaction entre les contraintes effectives et la pression interstitielle. Ainsi, les techniques de modélisation numérique avancées qui considèrent le couplage hydro-mécanique survenant dans la structure de la digue ont été développées. Ces modèles procurent un aperçu plus précis du comportement géotechnique de la digue à résidus. Cependant, les deux approches LEM et modélisation numérique sont déterministe. Par conséquent, ces approches ne tiennent pas compte de l'incertitude inhérente aux propriétés des matériaux de construction et ceci est un fait bien connu par l'ingénieur géotechnicien et pourtant ceci doit être abordé.Dans cette thèse, les approches d'analyse stochastiques tels que le Monte Carlo (MC) sont adoptées pour étudier l'effet de l'incertitude inhérente aux propriétés du matériau sur le coefficient de sécurité. Les deux LEM et les modèles numériques hydro- mécaniques couplés sont d'abord développés et après les résultats des modèles déterministes sont compilés. Ces derniers sont ensuite comparés aux résultats obtenus à partir des analyses stochastiques.Une étude de cas d'une nouvelle conception d'une digue à rétention d'eau à résidus avec des données géotechniques bien documentées est adoptée dans cette étude. Tout d'abord, l'analyse LEM a été poursuivi et suivi par une analyse de sensibilité pour déterminer les paramètres les plus influents sur le facteur de sécurité de la conception.Ensuite, un model couplé d'hydro-mécanique a été développé avec FLAC2D dans lequel la séquence de construction a été simulée en sept étapes. Le coefficient de sécurité (FOS) a été calculé à la fin de chaque étape en utilisant la technique de réduction de la résistance (SRT). Par la suite, la méthode d'estimation ponctuelle (PEM) a été utilisée pour obtenir la probabilité d'un rendement insatisfaisant en tenant compte de l'angle de base de la digue, de la friction, de la cohésion et de la perméabilité comme variables stochastiques. Le coefficient de variation des propriétés du matériau a été varié et ses conséquences sur la probabilité ont été enregistrées. Ensuite, la méthode de MC a été adoptée pour calculer la probabilité de rendement insatisfaisant de la digue à résidus ainsi que sa fiabilité. Par ailleurs, l'effet de la modification de la fonction de densité de probabilité (PDF) du paramètre d'entrée stochastique sur la fiabilité de sortie a encore été analysé. En outre, l'effet du hasard au niveau local a été étudiée en utilisant le hasard Monte-Carlo (RMC) et la méthode par rapport à la sortie de la méthode de MC. Enfin, l'effet du coefficient de corrélation entre l'angle de friction du noyau et la cohésion sur la fiabilité de la digue a été analysé. Ceci a été suivi d'une analyse stochastique avancé à l'aide de la méthode MC qui comprenait une troisième variable stochastique qui est la perméabilité du noyau. L'incorporation de paramètres à la fois mécaniques et hydrauliques en tant que variables stochastiques ont réduit la fiabilité de la digue, ainsi, mettant en évidence l'impact de l'analyse stochastique hydro-mécanique avec l'approche hybride. Les résultats de toutes les analyses sont présentés dans la thèse suivante ainsi que les découvertes dans la conclusion.
21
Orazalin, Zhandos Y. "Analysis of large deformation offshore geotechnical problems in soft clay." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111442.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2017.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 269-281).<br>Although finite element (FE) methods are well established for modeling geotechnical problems in soil masses and soil-structure interaction, most prior research on large deformation problems has been limited to simplified assumptions on drainage conditions and constitutive behavior. This thesis investigates two large deformation problems in soft clay and proposes a methodology for performing coupled flow and deformation analyses with advanced effective stress models. The first part of the research focuses on realistic 3-D finite element analyses (using AbaqusTM Standard) of a conductor (steel pipe pile) embedded within soft marine clay subjected to large lateral deformations caused by drift/drive-off of a drilling vessel. The proposed analyses use coupled pore pressure-displacement procedures together with the MIT-E3 soil model to represent the anisotropic, non-linear and inelastic effective stress-strain-strength properties of deepwater marine sediments with input parameters derived from a series of laboratory element tests performed on reconstituted Gulf of Mexico (GoM) clay. The numerical predictions are evaluated through comparison with experimental results from centrifuge tests with a well-instrumented model conductor. The FE results accurately predict the measured bending moment distribution along the length of the conductor and the spread of plastic strains within the conductor itself. The study has also shown the effects of soil behavior on local pile-soil interactions, enabling simplified analyses using macro-elements. The FE results have been used to calibrate input parameters for BWGG framework (Gerolymos & Gazetas, 2005), the Bouc-Wen (BW) model extended by Gerolymos and Gazetas (GG), that simulates generalized hysteretic pile-soil interactions and allows for degradation in soil resistance associated with geometric non-linearities. The second application considers the effects of partial drainage for large deformation, quasi-static piezocone penetration in clay. The proposed axisymmetric FE analysis procedure introduces automated remeshing and solution mapping technique (similar to RITSS; Hu & Randolph, 1998) within a commercial FE solver. We have analyzed the penetration resistance for a piezocone device using two elasto-plastic soil models (MCC, MIT-E3) and the recent elasto-viscoplastic MIT-SR soil model (Yuan, 2016) over a range of steady penetration velocities. The MCC predictions are in very good agreement with laboratory measurements of tip resistance and penetration pore pressures measured in centrifuge model tests in reconstituted kaolin. The results from more advanced soil models illustrate the impacts of anisotropic, rate dependent soil behavior on penetration tests in natural clays and are within the range of empirical measurements. The proposed analyses provide a complete framework that can now be used to investigate effects of partial drainage that occurs in piezocone tests for soils (such as silts) of intermediate permeability.<br>by Zhandos Y. Orazalin.<br>Ph. D.
22
Janrungautai, Sirisin. "The Study on Uncertainty Modeling and Risk Analysis Geotechnical Problems." 京都大学 (Kyoto University), 2003. http://hdl.handle.net/2433/148293.
Full text
23
Zhao, Tao. "Investigation of landslide-induced debris flows by the DEM and CFD." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:316cb3fc-dfc6-4e5a-bc0d-298e298c9c5b.
Full textAbstract:
In recent years, the increasing impacts of landslide hazards on human lives and lifeline facilities worldwide has advanced the necessity to find out both economically acceptable and useful techniques to predict the occurrence and destructive power of landslides. Though many projects exist to attain this goal, the current investigation set out to establish an understanding of the initiation and propagation mechanisms of landslides via numerical simulations, so that mitigation strategies to reduce the long-term losses from landslide hazards can be made. In this research, the Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD) have been used to investigate the mechanical and hydraulic behaviour of granular materials involved in landslides. The main challenge is to provide rational analyses of large scale landslides via small scale numerical simulations. To solve this problem, dimensional analyses have been performed on a simple granular column collapse model. The influence of governing dimensionless groups on the debris runout distance and deposit height has been studied for the terrestrial and submerged granular flows. 3D DEM investigations of granular flows in plane strain conditions have been performed in this research. The input parameters of the DEM model have been calibrated by the numerical triaxial tests, based on which, the relationships between the microscopic variables and the macroscopic soil strength properties are analysed. Using the simple granular column collapse model, the influences of column aspect ratio, characteristic strain, model size ratio and material internal friction angle on the runout distance and deposit height of granular materials have been examined. Additionally, the deformation and energy evolution of dry granular materials are also discussed. The DEM-CFD coupling model has been employed to study the mechanical and hydraulic behaviour of highly mobilized terrestrial / submarine landslides. This model has been validated via numerical simulations of fluid flow through a porous soil sample and grain batch sedimentations. The simulations of granular flows in the submerged environment have led to some meaningful insights into the flow mechanisms, such as the mobilization of sediments, the generation and dissipation of excess pore water pressures and the evolution of effective stresses. Overall, this study shows that the proposed numerical tools are capable of modelling the mechanical and hydraulic behaviour of terrestrial and submarine landslides.
24
Del, Potro Rodrigo. "Geotechnical analysis of the stability of stratovolcanoes : Teide edifice, Canary Islands." Thesis, Lancaster University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.514452.
Full text
25
Warren, Sean N. "Limit equilibrium stability analysis utilizing geotechnical data at Mount Baker, Washington /." abstract and full text PDF (UNR users only), 2008. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1461537.
Full textAbstract:
Thesis (M.S.)--University of Nevada, Reno, 2008.<br>"December 2008." Includes bibliographical references (leaves 109-112). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2009]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web. Library also has electronic version on CD-ROM
26
ARAUJO, LUIZ GONZAGA DE. "NUMERICAL STUDIES OF THE STABILITY OF GEOTECHNICAL MATERIALS THROUGH LIMIT ANALYSIS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1997. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=2084@1.
Full textAbstract:
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR<br>O presente trabalho apresenta um estudo de problemas de
estabilidade, freqüentemente,encontrados, em Engenharia
Geotécnica, através da técnica da Análise Limite associada
ao Método dos Elementos Finitos (MEF).Inicialmente, faz-se
uma revisão das formulações da Análise Limite, via
MEF,encontradas, com maior freqüência, na literatura
técnica especializada.Uma formulação mista que é descrita
em detalhe na tese foi escolhida para implementação.
Extensões das formulações da Análise Limite de meios
contínuos são propostas para contemplar características de
maciços rochosos fraturados. É proposto,também, um
procedimento numérico para tratar de problemas de
estabilidade de meios que exibem fluxo plástico não
associado.As implementações realizadas foram validadas
através de problemas cujas soluções
podem ser obtidas por via analítica.Finalmente, um número
considerável de problemas de interesse em Engenharia
Geotécnica é estudado utilizando a implementação realizada.
Os resultados destes estudos sugerem a viabilidade da
utilização da técnica estudada na solução de problemas
práticos de Engenharia Civil.<br>This work presents a study of stability problems often
encountered in Geotechnical Engineering, through the use of
Limit Analysis in conjunction with the Finite Element Method
(FEM).Initially, a literature survey of the most often
found formulations in Limit Analysis through the FEM is
carried out.A mixed formulation of Limit Analysis was
chosen for implementation and its details are fully
described. Extensions of the formulation to deal with
stability problems in fractured rock media are also
proposed and described. A numerical procedure to take into
account the effect of non associative plastic flow is
proposed.The implementations carried out were validated
through problems to which analytical solutions could be
found.Finally, a considerable number of problems of
interest to Geotechnical Engineering is studied with the
implemented formulation. The results of these studies
suggest that Limit Analysis can be considered as a viable
tool in the solution of practical problems in Geotechnical
Engineering.
27
Knutsson, Roger. "Tailings Dam Performance : Modeling and Safety Analysis of a Tailings dam." Licentiate thesis, Luleå tekniska universitet, Geoteknologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-18084.
Full textAbstract:
Storage and management of mine waste are both needed in the mining industry. After mineral extraction of the ore, there are generally leftovers with insufficient economical value that need to be taken care of. The finest grained fractions are referred to as tailings. Since every mine site and every tailings impoundment is unique, there is unfortunately not an universal answer to proper management that can be applied everywhere. Even though local guidelines and regulations can be considered to give a best practice in terms of design, there is correspondingly a need for dam safety stewardship on an operational level. Without such stewardship, not even the best designed dams or facilities would be fully controlled in terms of safety. Conversely, even badly designed dams can be operated in safe manners with good stewardship and surveillance programs. The coupling between design and stewardship is therefore important in order to reach proper tailingsmanagement.In the design of tailings dams, a certain value of the factor of safety for slopes of the dams is normally striven for to secure stability. The value is generally based on national regulations and/or guidelines. In Sweden the factor of safety should not be lower than 1.5 under normal conditions. In the guidelines, recommendations are often given on dam surveillance and field measurements of e.g. pore water pressure, deformations and seepage. Field measurements are taken, but are generally assessed in terms of trends (change with time) and not by comparison to anticipated performance.In this study, numerical modeling has been used for stability analyses and dam performance, as predictions of deformations and pore water pressure levels. An upstream tailings dam located in northern Sweden has been used as a case. The granular materials being part of the model based were described based upon geotechnical investigations (field and lab). The tailings material was modeled, on a constitutive level, by the Hardening Soil model. Good agreement betweensimulated behavior and laboratory tests was achieved. Other dam materials were simulated by the Mohr-Coulomb model.The model was built as a staged construction model where historical events between 1992 and 2013 were simulated. The historical events included dam raises, increased beach elevations, remedial works etc. The simulations of historical events were used for facilitating comparison with field measurements. By means of inclinometer data, horizontal deformations were measured and evaluated for a period of six years. These deformations were accurately simulated, which was considered to verify the numerical model. By this verification, the model is considered accurate enough to be used for simulating future events. Both stability and corresponding dam performance were computed, by simulating a period of 10 years. The stability analyses were used for the set-up of rockfill support plans, i.e. where and when remedial works are needed in order to maintain a certain safety level. The corresponding values in deformations and pore water pressures were used for the set-up of alert levels for each measuring unit. These alert levels will help the engineer in field with data interpretation, where the simulated values are compared with field measurements taken. The proposed methodology is recommended for tailings dams in general, which reduces the gap between design and stewardship. Hence, one step closer to proper tailings management is taken.<br>Godkänd; 2015; 20151026 (rogknu); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Roger Knutsson Ämne: Geoteknik/Soil Mechanics Uppsats: Tailings Dam Performance Modeling and Safety Analysis of a Tailings Dam Examinator: Professor Sven Knutsson Institutionen för samhällsbyggnad och naturresurser Avdelning Geoteknologi Luleå tekniska universitet Diskutant: Technical Director Annika Bjelkevik Tailings Consultant Scandinavia AB Stockholm Tid: Fredag 27 november 2015 kl 13.00 Plats: F1031, Luleå tekniska universitet
28
Chabuk, Ali Jalil. "Analysis of Landfill Site Selection-Case Studies Al-Hillah and Al-Qasim Qadhaas, Babylon, Iraq." Licentiate thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-347.
Full textAbstract:
The selection of a landfill site is considered as a complicated task because the whole process is based on many factors and restrictions. This study shows the present status of solid waste management, solid waste sources, staffing for solid waste collection, machinery and equipment used in the waste collection process, finance and financial management at Babylon Governorate and its Qadhaa. The management of collection and disposal of waste in Babylon Governorate and its Qadhaa is done through open dumping of waste and the quality of the collection process is poor. This is the case in Al-Hillah Qadhaa, which is located in the central part of the governorate, Iraq and Al-Qasim Qadhaas, which is situated in the southern part of the Babylon Governorate, Iraq. These sites do not conform to the scientific and environmental criteria applied in the selection of landfill sites. In the first part of the current study, to find out how much solid waste will be produced in the future; two methods were used to calculate the population growth in Al-Hillah and Al-Qasim Qadhaas to the year 2030. The results showed that the total waste in 2030 according to the first and second methods respectively will be 394,081 tonnes and 472,474 tonnes in Al-Hillah Qadhaa, and (54,481 tonnes and 76,374 tonnes) in Al-Qasim Qadhaa. The cumulated quantity of solid waste expected to be produced between 2020 and 2030 according to the first and second methods respectively was 3,757,387 tonnes and 4,300,864 tonnes in Al-Hillah Qadhaa, whilst in Al-Qasim Qadhaa it was 519,456 tonnes and 695,219 tonnes. The generation rate in 2020 will be (0.88 and 0.62) kg/ (capita. day) in Al-Hillah and Al-Qasim Qadhaas respectively; in year 2030, the generation rate will be (0.97 and 0.69) kg/ (capita. day) based on method 2 and an expected incremental increase in generation rate of 1 kg/ (capita. day) per year. The second part of this study aims to find the best sites for landfills in Al-Hillah and Al-Qasim Qadhaas. For this reason, 15 criteria were adopted in this study (groundwater depth, rivers, soil types, agricultural land use, land use, elevation, slope, gas pipelines, oil pipelines, power lines, roads, railways, urban centres, villages and archaeological sites) using GIS (geographic information system), which has a large capacity for managing input data. In addition, the AHP (analytical hierarchy process) method was used to derive the relative weightings for each criterion using pairwise comparison. The suitability index map for candidate landfill sites was obtained. Two suitable candidate landfill sites were found to fulfill the scientific and environmental requirements in each Qadhaa, with areas of 9.153 km2 and 8.204 km2 respectively in Al-Hillah Qadhaa, and with areas of 2.766 km2 and 2.055 km2 respectively in Al-Qasim Qadhaa. The area of these sites can accommodate solid waste from 2020 until 2030 based on the required areas, which were 4.175 km2 and 4.778 km2 (Ali-Hillah Qadhaa) and 0.577 km2 and 0.772 km2 in (Al-Qasim Qadhaa) according to the first and second methods respectively.
29
Prasad, Anamika 1979. "Development of user interface for numerical limit analysis of geotechnical stability problems." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/85751.
Full text
30
Hardy, Stuart. "The implementation and application of dynamic finite element analysis to geotechnical problems." Thesis, Imperial College London, 2003. http://hdl.handle.net/10044/1/7146.
Full text
31
Kolat, Cagil. "Developing A Geotechnical Microzonation Model For Yenisehir (bursa) Settlement Area." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612163/index.pdf.
Full textAbstract:
The purpose of this study is to develop a geotechnical microzonation model
regarding the suitability of the residential areas in Yenisehir (Bursa, Turkey),
which is a currently developing settlement area in a seismically active region. For
this purpose, soil properties and dynamic soil behaviors of the study area were
assessed. Soil classification, soil amplification, natural soil predominant period,
resonance phenomena and liquefaction potential of the study area were
evaluated using borehole data and microtremor measurements. The raw data
obtained from the previous studies carried out at Yenisehir were used for these
assessments. The liquefaction potential for the study area was evaluated both in
two-dimensional planimetric and three-dimensional volumetric assessments. Two
geotechnical microzonation maps were produced for the study area according to
the surface damage due to liquefaction (according to two different methods), soil
amplification and distance to streams maps<br>by using Geographical Information
Systems (GIS) based Multi-Criteria Decision Analysis. The weight values were
assigned to the layers using Analytical Hierarchical Process method by pairwise
comparisons. Evaluating geotechnical microzonation maps produced, the safest
areas were found on the northern sites of the study area. The most critical areas
were found to be in the middle and the southeast parts of the study area.
32
Peeters, Bieke. "Two-dimensional analysis of the failure mechanisms of an embankment supported by rows of dry deep mixing columns." Thesis, KTH, Jord- och bergmekanik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-208177.
Full text
33
Bertel, Jeffrey D. "Analytical study of the spectral-analysis-of-surface-waves method at complex geotechnical sites." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4625.
Full textAbstract:
Thesis (M.S.) University of Missouri-Columbia, 2006.<br>The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 21, 2007) Includes bibliographical references.
34
Arulrajah, Atputharajah. "Field measurements and back-analysis of marine clay geotechnical characteristics under reclamation fills." Curtin University of Technology, Department of Civil Engineering, 2005. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=16008.
Full textAbstract:
Due to the scarcity of land at coastal regions around the world, land reclamation is commonly carried out for the future expansion of various infrastructure facilities. Marine clay is present at the coastal regions of Southeast Asia. Land reclamation on this highly compressible soil foundation often requires the use of soil improvement works to eliminate significant future settlements from occurring. The combination of prefabricated vertical drains with preloading is one of the most widely used ground improvement methods in land reclamation projects. The best means available for field measurement and back-analysis of the marine clay geotechnical characteristics under reclamation fills is by carrying out extensive field instrumentation and in-situ tests. In-situ testing of marine clay was carried out at a test site. In-situ penetration testing was used to analyse the degree of consolidation, the improved shear strengths, overconsolidation ratio and the effective stress of marine clay prior to reclamation as well as after surcharge loading. In-situ dissipation testing was used to determine the coefficient of consolidation due to horizontal flow and horizontal hydraulic conductivity of the marine clay prior to reclamation as well as after surcharge loading. The in-situ penetration and dissipation tests were carried out by means of the field vane shear, piezocone, dilatometer, self-boring pressuremeter and BAT permeameter. Field instrumentation methods, assessment and hack-analysis of marine clay behaviour under reclamation fills forms the crux of this research.<br>The factors that affect the field instrumentation assessment of marine clays treated with prefabricated vertical drains, forms an integral part of this research study. Settlement gauges and piezometers were used to monitor the performance of the vertical drains and to assess the degree of consolidation of the improved soil at two case study sites. The field settlement data were back-analysed by the Asaoka and Hyperbolic methods to predict the ultimate settlement of the reclaimed land under the surcharge fill. Back-analysis of the field settlement and piezometer monitoring data also enabled the coefficient of consolidation due to horizontal flow to be closely estimated. Finite element modeling of marine clay and prefabricated vertical drains was carried out and compared with the field surface settlement results at the two case study sites.
35
McKay, Sara E. "Geotechnical analysis of horizontal drains as a landslide mitigation method in western Washington /." abstract and full text PDF (free order & download UNR users only), 2006. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1437660.
Full textAbstract:
Thesis (M.S.)--University of Nevada, Reno, 2006.<br>"August, 2006." Includes bibliographical references (leaves 93-97). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2006]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.
36
Kontoe, Stavroula. "Development of time integration schemes and advanced boundary conditions for dynamic geotechnical analysis." Thesis, Imperial College London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435799.
Full text
37
Hicks, Malcolm Andrew. "Geotechnical Investigations of Wind Turbine Foundations Using Multichannel Analysis of Surface Waves (MASW)." Thesis, University of Canterbury. Geological Sciences, 2011. http://hdl.handle.net/10092/6519.
Full textAbstract:
The geophysical technique known as Multichannel Analysis of Surface Waves, or MASW (Park et al., 1999) is a relatively new seismic characterisation method which utilises Rayleigh waves propagation. With MASW, the frequency dependent, planar travelling Rayleigh waves are created by a seismic source and then measured by an array of geophone receivers. The recorded data is used to image characteristics of the subsurface.
This thesis explains how MASW was used as a geotechnical investigation tool on windfarms in the lower North Island, New Zealand, to determine the stiffness of the subsurface at each wind turbine site. Shear‐wave velocity (VS) profiles at each site were determined through the processing of the MASW data, which were then used to determine physical properties of the underlying, weathered greywacke.
The primary research site, the Te Rere Hau Windfarm in the Tararua Ranges of the North Island, is situated within the Esk Head Belt of Torlesse greywacke (Lee & Begg, 2002). Due to the high level of tectonic activity in the area, along with the high rates of weathering, the greywacke material onsite is highly fractured and weathering grades vary significantly, both vertically and laterally. MASW was performed to characterise the physical properties at each turbine site through the weathering profile. The final dataset included 1‐dimensional MASW shear‐wave evaluations from 100 turbine sites. In addition, Poisson’s ratio and density values were characterised through the weathering profile for the weathered greywacke. During the geotechnical foundation design at the Te Rere Hau Windfarm site, a method of converting shear wave velocity profiles was utilised. MASW surveying was used to determine VS profiles with depth, which were converted to elastic modulus profiles, with the input parameters of Poisson’s ratio and density.
This study focuses on refining and improving the current method used for calculating elastic modulus values from shear‐wave velocities, primarily by improving the accuracy of the input parameters used in the calculation.
Through the analysis of both geotechnical and geophysical data, the significant influence of overburden pressure, or depth, on the shear wave velocity was identified. Through each of the weathering grades, there was a non‐linear increase in shear wave velocity with depth. This highlights the need for overburden pressure conditions to be considered before assigning characteristic shear wave velocity values to different lithologies.
Further to the dataset analysis of geotechnical and geophysical information, a multiple variant non‐linear regression analysis was performed on the three variables of shear wave velocity, depth and weathering grade. This produced a predictive equation for determining shear wave
velocity within the Esk Head belt ‘greywacke’ when depth and weathering data are known. If the insitu geological conditions are not comparable to that of the windfarm sites in this study, a set of guidelines have been developed, detailing the most efficient and cost effective method of
using MASW surveying to calculate the elastic modulus through the depth profile of an
investigation site.
38
FARFAN, ALDO DURAND. "APPLICATIONS OF LIMIT ANALYSIS TO GEOTECHNICAL PROBLEMS MODELLED AS CONVENTIONAL AND COSSERAT CONTINUA." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2000. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=2000@1.
Full textAbstract:
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO<br>O presente trabalho trata da aplicação da análise limite
numérica (ALN) a problemas geotécnicos. Os meios (solo ou
rocha) são considerados como contínuos convencionais e como
contínuos de Cosserat.
Da aplicação da formulação mista da análise limite e da
discretização do meio por uma malha de elementos finitos é
obtido um problema de programação matemática (PM).
A aplicação desta metodologia nos contínuos de Cosserat
(2D) fornece problemas de programação linear (PL) e nos
contínuos convencionais (2D e 3D), problemas de
programação não-linear (PNL).
A solução do problema de PM foi através dos programas de
otimização: LINDO (PL), LINGO (PNL), MINOS (PNL) e LANCELOT
(PNL). Também foram implementados os algoritmos não
lineares -Quase Newton com deflexão- e -Han-Powell-.
A formulação é validada em problemas cuja solução analítica
é conhecida ou em dados experimentais. Estes exemplos
mostram a rapidez e a eficácia da ALN para a determinação
da carga de colapso e do mecanismo de ruptura do problema.<br>The present work treats of the application of the numerical
limit analysis (NLA)to geomechanics problems. The soil or
rock mass is considered as conventional continuous and
Cosserat continuous. A mathematical programming (MP)
problem is obtained through the application of the mixed
formulation of limit analysis and the finite elements mesh.
The application of this methodology in the Cosserat
continuous (2D) supplies linear programming (LP)
problems and in the conventional continuous (2D and 3D)
nonlinear programming (NLP) problems. The solution of the
problem of MP was through the LINDO (LP), LINGO (NLP),
MINOS (NLP) and LANCELOT (NLP) programs. It was also
implemented nonlinear algorithms -Quasi-Newton feasible
point method- and -Han-Powell-.The formulation is validated
in problems whose analytic solution is known or in
experimental data. These examples show the speed and the
effectiveness of NLA for the determination of the collapse
load and of the mechanism of rupture of the problem.<br>EL presente trabajo trata de la aplicación del análisis
límite numérica (ALN) a problemas geotécnicos. Los medios
(suelo o roca) son considerados como contínuos
convencionales y como contínuos de Coserat. De la
aplicación de la formulación mixta del análisis límite y de
la discretización del medio por una malla de elementos
finitos se obtiene un problema de programación matemática
(PM). La aplicación de esta metodología en los contínuos de
Coserat (2D) nos lleva a problemas de programación lineal
(PL) y en los contínuos convencionales (2D y 3D), problemas
de programación no lineal (PNL). La solución del problema
de PM fue a través de los programas de optimización: LINDO
(PL), LINGO (PNL), MINOS (PNL) y LANCELOT (PNL). También
fueron implementados los algoritmos no lineares quase-
Newton con deflexión y Han Powell . Se evalúa la
formulación propuesta en problemas donde se conoce la
solución analítica o en datos experimentales. Estos
ejemplos muestran la rapidez y la eficacia de la ALN para
la determinación de la carga de colapso y del mecanismo de
ruptura del problema.
39
Madden, Patrick. "The influence of structural details, geotechnical factors and environs on the seismic response of framed structures." Thesis, University of Dundee, 2014. https://discovery.dundee.ac.uk/en/studentTheses/c24ae223-999c-407c-bd3f-b461708dcbb3.
Full textAbstract:
Seismic events around the globe directly affect all ranges of structures, from complex and expensive ‘skyscrapers’ to simple frame structures, the latter making up a higher proportion of the number of structures affected as they are a much more common type of structure. The impact of a seismic event can be devastating, especially if adequate predictions of their impact and imposed structural response are not made during the design stage of the structure. Knowing what response to expect allows the engineer to design the structure to survive an event and protect the occupants. The structural response to a seismic event is very complex and can be affected by a wide range of structural, geotechnical and environ parameters. While larger, expensive structures make use of expensive, time consuming, finite element analytical procedures to determine their response the cheaper, simpler, frame structures have to make do with existing, simplified, spectral method predictions. This research firstly involves finite element analysis of simple frame structures, considering different structural and geotechnical parameters which may influence the seismic response, namely the stiffness of the structural joints, the geometry of the structure (influencing the individual structural element flexibility) and the foundation conditions (fixed base or shallow foundations with soil structure interaction). A range of frames, of varying geometry, are considered which mobilise different amounts of inter-storey drift, local rotation and global rotation response. The influence of soil structure interaction (SSI) and frame rigidity (i.e. the properties of the joints) on the response behaviour is investigated. The finite element database is then used to validate improved methods for predicting the spectral response parameters, specifically the natural period and damping of equivalent single degree of freedom (SDOF) systems, which include the effects of frame rigidity, geometry and SSI. Dynamic centrifuge testing is also carried out in order to further validate the improved spectral model for the case of real soil with shear dependant stiffness. The physical model testing is also extended to consider how environs, such as other structures in close proximity, influence the response of a structure.
40
Finlayson, K. A. "Geophysical evaluation of the geotechnical properties of Quaternary sediments from the continental margin, northwest of the UK." Thesis, Bangor University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310918.
Full text
41
Majala, Jonas. "Frequency analysis of accelerometer measurements on trains." Thesis, Luleå tekniska universitet, Geoteknologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-63930.
Full text
42
Hürlimann, Marcel. "Geotechnical analysis of large volcanic landslides: The La Orotava events on Tenerife,Canary Islands." Doctoral thesis, Universitat Politècnica de Catalunya, 1999. http://hdl.handle.net/10803/6217.
Full textAbstract:
Los grandes deslizamientos volcánicos son uno de los procesos geológicos más devastadores y pueden representar un importante peligro para la población de las zonas volcánicas. Este tipo de deslizamientos puede sobrepasar volúmenes de decenas o incluso centenares de kilómetros cúbicos. En Tenerife, siete grandes deslizamientos han afectado durante los últimos ~6 millones de años la morfología subaérea y submarina de la isla.<br/>En este estudio se ha realizado un extenso análisis de los eventos que han formado el valle de "La Orotava" en la parte Norte de Tenerife. El estudio incluye una investigación de campo, ensayos de laboratorio y análisis de estabilidad. En el laboratorio, las propiedades mecánicas de un suelo residual han sido investigadas mediante cortes directos y ensayos triaxiales. Durante el análisis de estabilidad, los resultados de los ensayos de laboratorio han sido incorporados a diferentes tipos de modelos de estabilidad. Finalmente, las condiciones mecánicas de los modelos dos y tres dimensionales han sido estudiados mediante el método de equilibrio límite y métodos de elementos finitos.<br/>Los resultados de los análisis revelan que la estabilidad de las laderas volcánicas puede ser reducida debido a diversos factores, como geológicos, morfológicos, climáticos y volcánicos. Los suelos residuales - bastante comunes en Tenerife - pueden haber actuado como superficie de rotura a causa de su débil comportamiento mecánico. Por otra parte, los estrechos y profundos barrancos han definido los límites laterales de los deslizamientos. Además de ello, los acantilados, el clima húmedo y especialmente la constante intrusión de diques, han llevado la ladera a condiciones de estabilidad críticas. Finalmente, una aceleración sísmica causada por un seísmo fuerte y cercano provocó muy probablemente el deslizamiento catastrófico.<br/>En Tenerife, se ha observado una relación temporal entre los colapsos de caldera y los grandes deslizamientos, lo que permite suponer que los fuertes terremotos asociados a los colapsos de caldera hayan provocado los deslizamientos.<br>Large volcanic landslides are one of the most hazardous of geological processes. They have occurred about once every 25 years during the last 500 years, and are a serious risk for the population due to their great volume and mobility. In spite of their destructive potential there are few comprehensive studies analysing large landslides on volcano flanks, and the mechanisms of such mass movements are not yet resolved. Within the last few years, several hypotheses concerning the potential causes of volcanic landslides have been proposed including processes such as dike intrusion, volcanic spreading, hydrothermal alteration, seismic shocks and caldera collapse events.<br/>Tenerife exhibits three large subaerial valleys originated by giant flank failures with ages ranging from Upper Pliocene to Middle Pleistocene. The northern submarine flank of the island is characterised by a voluminous apron of landslide debris. The La Orotava valley has been selected for analysis due to the amount of available data concerning its structure and evolution, and has been used as a test site to validate new assumptions that could be applied to other volcanic areas. <br/>The site investigation has revealed that the present morphology of the La Orotava valley was formed by two different failures: one in the western sector and the other in the eastern sector. The mechanical stability of the preslide volcano flank was strongly reduced by geologic, morphologic, climatic and volcanological factors which play a fundamental role in the initiation of the landslides. Widespread residual soils (paleosols) might have acted as potential slip surfaces, while deep erosive canyons probably evolved into the lateral limits of the failures. A high coastal cliff and a humid climate have also contributed to the critical stability conditions. The location of the landslide amphitheatre is perpendicular to the active Dorsal rift zone and adjacent to the Las Cañadas caldera, both important influences on the stability of the volcano slopes. On Tenerife, the relationship between large volcanic landslides and vertical caldera collapses is supported by a temporal coincidence of at least two failures with caldera collapse events.<br/>The mechanical behaviour of a residual soil sampled in the La Orotava valley has been analysed. Red coloured residual soils are generally located at the top of phonolitic pyroclastic deposits and are proposed as potential slip surfaces due to their very weak behaviour and their flat, homogeneous characteristics. They represent the only planar surface within the succession making up the volcano slopes. Their weak mechanical behaviour is characterised by volumetric collapse during shearing, a substantial reduction of shear strength for high normal stresses, and a significant increase of pore water pressure during undrained loading. The last feature is fundamental to the stability of volcano flanks since it strongly reduces the soil strength. Earthquakes, common processes in active volcanic areas, and saturated conditions can generate high excess pore pressures indicating the importance of regional climate and seismicity. <br/>The stability analysis has considered three different mechanisms: 1) ground acceleration due to seismicity - including both tectonic earthquakes and volcano-tectonic seismic shocks produced by caldera collapse; 2) horizontal stress due to dike intrusion, and; 3) vertical shear stress due to caldera collapse. The results indicate that ground acceleration principally decreases the mechanical stability of volcano flanks, enabling failure. Horizontal stresses due to dike intrusion can also influence slope stability, but preferably act as a preparing factor destabilising the slope, and not as a final triggering mechanism. The 3D numerical simulations show the significant effect of deeply incised canyons creating high shear stress at their base. <br/>Applying the results to the La Orotava events, the following scenario is assumed: First, deep narrow canyons, weak residual soils, humid climate, coastal cliff and persistent dike intrusion have significantly reduced the mechanical stability of the volcano slope and determined the limits of the failing mass. Then, seismicity generated by the caldera collapse episode at the end of the Guajara cycle at ~0.56 Ma triggered the catastrophic landslides.<br/>The results of the mobility analysis show the important influence of water on the runout distances of landslides. Subaqueous drag forces reduce the velocity, while hydroplaning effects strongly increase the runout distance. For Tenerife, the model indicates that a sliding mass can advance great distances, tens of kilometres away from the island, at water depths exceeding 3000 m, as can be observed in the bathymetric data.
43
Javakhishvili, Zurab. "The coupled finite-boundary element method applied to the analysis of geotechnical engineering problems." Thesis, London South Bank University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261020.
Full text
44
Han, Bo. "Hydro-mechanical coupling in numerical analysis of geotechnical structures under multi-directional seismic loading." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/28683.
Full textAbstract:
This thesis numerically investigates the seismic behaviour of geotechnical structures under multi-directional loading by employing the coupled hydro-mechanical (HM) formulation of the Imperial College Finite Element Program (ICFEP). The scope of the research work can be summarised as follows: Firstly, the stability of the generalised-α method (CH method) for the coupled consolidation formulation, is analytically investigated for the first time and the corresponding theoretical stability conditions are derived. The analytically derived stability conditions are validated by finite element (FE) analyses considering a range of loading conditions and soil permeability values. Secondly, the site response due to the vertical component of the ground motion is systematically investigated by employing analytical and numerical methods. The compressional wave propagation mechanism in saturated porous soils is investigated by the coupled HM formulation. Furthermore, the undertaken coupled FE analyses explore the effects of the parameters characterising the hydraulic phase, i.e. the soil permeability and soil state conditions, on the vertical site response. Thirdly, three-directional (3-D) site response analyses are conducted for the HINO site of the Japanese KiK-net down-hole array earthquake monitoring system. Different aspects of the numerical modelling for the site response analysis, such as the constitutive model, the use of 3-D input motion and the coupled consolidation formulation, are investigated and validated by the recordings from the KiK-net system. Further parametric studies investigate the impact of the variation of the water table, the soil permeability and the 3-D input motion on the multi-directional site response. Finally, the seismic response of a well-documented Chinese rockfill dam, the Yele dam, is investigated with the dynamic plane-strain FE analysis, accounting for the HM coupling and nonlinear soil response. The numerical predictions are compared against the available static and dynamic monitoring data, which allows for a rigorous validation of the developed numerical model. Furthermore, parametric studies of the Yele dam are conducted to explore the effects of several critical factors on the seismic response of rockfill dams, i.e. the reservoir simulation method, the permeability of materials comprising the dam body, the vertical ground motion and the reservoir water level.
45
Dunne, Helen P. "Finite element limit analysis of offshore foundations on clay." Thesis, University of Oxford, 2017. http://ora.ox.ac.uk/objects/uuid:ba9c9beb-e055-4f46-a9f9-b2d10bd292b7.
Full textAbstract:
Capacity analysis is a common preliminary step in the design of offshore foundations. Inaccuracies in traditional capacity analysis methods, and the advancement of numerical modelling capabilities, have increasingly led designers to optimise foundations using more complex methods. In this thesis, the ultimate limit state capacity of a range of foundation types is investigated using finite element limit analysis. Novel three-dimensional finite element limit analysis software is benchmarked against analytical solutions and conventional displacement finite element analysis. It is then used to find lower and upper bounds of foundation capacity, with adaptive mesh refinement used to reduce the bound gap over successive iterations of the solution. Rigid foundations subjected to short term loading on clay soil are analysed. The undrained soil is modelled as a rigid--plastic von Mises material, and attention is given to modelling any normal and/or shear stress limits at the foundation/soil interface. Shallow foundations, suction anchor foundations, and hybrid mudmat/pile foundations are considered. Realistic six degree-of-freedom load combinations are applied and results are reported in the form of normalised design charts, and tables, that are suitable for use in preliminary design. Relationships between loading combinations and failure mechanisms are also explored. A number of case studies based on authentic foundation designs are analysed. The results suggest that finite element limit analysis could provide an attractive alternative to displacement finite element analysis for preliminary foundation design calculations.
46
Bossi, Giulia <1984>. "Statistical analysis of the error associated with the simplification of the stratigraphy in geotechnical models." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/6958/.
Full textAbstract:
The uncertainties in the determination of the stratigraphic profile of natural soils is one of the main problems in geotechnics, in particular for landslide characterization and modeling. The study deals with a new approach in geotechnical modeling which relays on a stochastic generation of different soil layers distributions, following a boolean logic – the method has been thus called BoSG (Boolean Stochastic Generation). In this way, it is possible to randomize the presence of a specific material interdigitated in a uniform matrix.
In the building of a geotechnical model it is generally common to discard some stratigraphic data in order to simplify the model itself, assuming that the significance of the results of the modeling procedure would not be affected. With the proposed technique it is possible to quantify the error associated with this simplification. Moreover, it could be used to determine the most significant zones where eventual further investigations and surveys would be more effective to build the geotechnical model of the slope. The commercial software FLAC was used for the 2D and 3D geotechnical model. The distribution of the materials was randomized through a specifically coded MatLab program that automatically generates text files, each of them representing a specific soil configuration. Besides, a routine was designed to automate the computation of FLAC with the different data files in order to maximize the sample number.
The methodology is applied with reference to a simplified slope in 2D, a simplified slope in 3D and an actual landslide, namely the Mortisa mudslide (Cortina d’Ampezzo, BL, Italy). However, it could be extended to numerous different cases, especially for hydrogeological analysis and landslide stability assessment, in different geological and geomorphological contexts.<br>L’incertezza nella determinazione del profilo stratigrafico e dei parametri meccanici dei singoli terreni è tra i principali problemi dell’ingegneria geotecnica, in particolare per l’analisi dei fenomeni franosi.
Lo studio presenta un nuovo approccio nella modellazione geotecnica che si basa sulla generazione stocastica di diverse distribuzioni di strati di terreno, seguendo una logica booleana - il metodo è stato perciò chiamato BoSG (Boolean Stochastic Generation – Generazione Stocastica Booleana). Con questo metodo è possibile randomizzare la presenza di uno specifico materiale interdigitato in una matrice uniforme.
Nell’impostare un modello geotecnico, infatti, generalmente si eliminano alcuni dati stratigrafici per semplificare il modello stesso, assumendo che la significatività dei risultati non ne risenta. La metodologia proposta permette di quantificare l'errore associato a questa semplificazione. Inoltre, può essere utilizzata per determinare le zone più significativi nelle quali possibili ulteriori indagini geotecniche sarebbero più efficaci per la definizione del modello geotecnico. Per la modellizzazione bidimensionale e tridimensionale è stato utilizzato il software commerciale alle differenze finite FLAC. La distribuzione dei materiali è stata randomizzata attraverso un programma in MatLab specificamente codificato che genera automaticamente dei file di testo con le configurazioni del terreno. E’ stata inoltre programmata una routine per automatizzare il calcolo FLAC con diverse file di dati al fine di massimizzare la numerosità campionaria.
In questa tesi la metodologia è stata applicata ad un pendio semplice in 2D, un pendio semplice in 3D e una frana reale: la frana di colata di Mortisa (Cortina d'Ampezzo, BL). Il metodo, tuttavia, potrebbe essere applicato ad altri casi, in particolare per studi di idrologia sotterranea, per l’analisi di stabilità di altre frane e in diversi contesti geologici e geomorfologici
47
Howie, C. T. "Computer program development for the analysis of inelastic beam and soil behaviour in geotechnical design." Master's thesis, University of Cape Town, 1992. http://hdl.handle.net/11427/18236.
Full textAbstract:
Computer-aided engineering requires the correct implementation of design methods in computer programs so as to play a beneficial role in engineering practice. This thesis describes the development of a computer program to analyse geotechnical engineering problems based on the principles of beam-soil interaction where the beam is supported by a single or two-layer soil system. In 1867, a foundation model was proposed by Winkler in which the elastic foundation beneath a horizontal beam could be viewed as a series of independent springs. Foundation reaction to beam deflection is, therefore, linear. A stiffness matrix, for use in matrix methods of structural analysis, has been developed to define this beam-soil interaction, and such a method can be incorporated into a computer program. Furthermore, an iterative technique was created to allow for inelastic soil response when using the elastic stiffness matrix. However, such a technique did not consider realistic soil behaviour, and has limitations is used for practical design. This research' work describes how use can be made of the pressure-displacement response relationship for a soil to bring greater realism to beam-soil modelling and analysis. Such a relationship is commonly determined in geotechnical design procedures through a plate load test in the field. In addition, the iterative technique is extended to include non-linear beam behaviour as well, and plastic hinging of the beam material is incorporated to enable limitation of inelastic response. While previous research has only considered foundations of a single soil only, a procedure to model a two-layered system is developed. Two-layered foundations are required for proper modelling of soldier pile support systems, an area of structural design in geotechnics chosen to demonstrate realistic design potential for the computer program. The two-layered principle is based on the derivation of a control parameter to differentiate between response from just the upper soil layer, and a combined response from both soil layers. The procedure is relatively simple, and no extra information is required other than the two pressure displacement relationships for the individual soil layers. A desktop computer program is described which incorporates the inelastic analysis features, as well as the two-layered soil system. The program makes use of a graphical user interface to offer the user an easy, interactive environment for analysing beam-on-soil foundation problems. As such, the program can be used directly, or for further research into beam-soil interaction. The program is applied in the analysis of both field and laboratory tests to ascertain its accuracy in predicting beam-soil interaction. The laboratory test measures the deflection of a horizontal beam on a single soil foundation medium, where the beam is loaded by a single jack at approximately mid-span. Computer predictions for such a test were in very close agreement with the laboratory observations, despite the small magnitude of beam displacements, and the fact the beam-soil system suffered a bearing capacity failure which affected the beam deflection. The field test was performed to investigate the performance of a flexible soldier pile under high anchor loading. Results of the computer analyses again show the program's predictions to be in very close agreement with the field measurements. Currently, the program does not include the facility to model soil layers behind a soldier pile, but the method developed in this thesis can easily incorporate multiple pressure-displacement curves for different soils. Final conclusions drawn express a need for more research into soldier pile systems before the techniques of this work can be used for routine design. Nevertheless, the development of the program has made a significant contribution to advancing the use of computer-aided design in this field of geotechnical engineering.
48
Shillaber, Craig Michael. "Toward Sustainable Development: Quantifying Environmental Impact via Embodied Energy and CO2 Emissions for Geotechnical Construction." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/64935.
Full textAbstract:
With rising awareness that future generations may not have access to the resources and quality of life that exist today, sustainable development has become a priority within civil engineering. One important component of sustainable development is environmental stewardship, which concerns both the resources taken from the environment, and the wastes and byproducts emitted to the environment. To facilitate more sustainable development, environmental accounting is necessary within civil and geotechnical engineering design and construction. Historically, geotechnical practice has focused on maximizing design performance while minimizing monetary costs, and well established methods exist for quantifying these factors. Quantitative consideration of environmental consequences has seldom played a large role in geotechnical design and construction, and clear guidelines and a methodology for such an assessment are not available within the geotechnical profession. Therefore, this research has focused on establishing a method for quantitative streamlined environmental Life Cycle Analysis of energy and carbon dioxide (CO2) emissions for geotechnical ground improvement works, known as the Streamlined Energy and Emissions Assessment Model (SEEAM). The boundaries for the SEEAM extend from raw material extraction through the completion of construction, including the energy and CO2 emissions associated with construction materials, construction site operations, and the transportation of construction materials and wastes. The methodology relies on energy and CO2 emissions coefficients, which represent typical industry average values and not necessarily the specific processes contributing to a project. Therefore, there is uncertainty in SEEAM analyses, which is addressed via a Monte Carlo simulation framework that assumes the energy and CO2 emissions coefficients each follow a lognormal distribution. Data sets of total energy and CO2 emissions generated by the Monte Carlo simulation framework with the SEEAM may be used to statistically compare the energy and CO2 emissions of different geotechnical design alternatives. Such comparisons can help facilitate designing for minimum environmental consequences, thus advancing sustainable development within geotechnical engineering. For clarity, the development and application of the SEEAM is illustrated using two different geotechnical case history projects, including rehabilitation of levee LPV 111 in New Orleans, LA, and the construction of foundations for a replacement dormitory on the Virginia Tech campus.<br>Ph. D.
49
He, Longxue [Verfasser], and Michael [Akademischer Betreuer] Beer. "Advanced Bayesian networks for reliability and risk analysis in geotechnical engineering / Longxue He ; Betreuer: Michael Beer." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2020. http://d-nb.info/1206685883/34.
Full text
50
He, Longxue Verfasser], and Michael [Akademischer Betreuer] [Beer. "Advanced Bayesian networks for reliability and risk analysis in geotechnical engineering / Longxue He ; Betreuer: Michael Beer." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2020. http://nbn-resolving.de/urn:nbn:de:101:1-2020031901080232795085.
Full text