Dissertations / Theses on the topic 'Earthen Embankments'

A comprehensive experimental program dealing with three-dimensional overtopping and breach development as well as two-dimensional overtopping physical tests of noncohesive earth embankments has been conducted on scale models in the Hydraulic Laboratory at the Department of Civil Engineering at the University of Ottawa. The experimental program which consisted of three phases focused on geotechnical and hydraulic aspects of the embankment breach mechanism. The first two phases focused on two test series for the three-dimensional breach overtopping tests: drainage and compaction. The test series were designed to determine the embankment breach characteristics using test parameters which have not been adequately identified or controlled in past noncohesive physical models: initial soil-water state and optimum dry unit weight. Both parameters were controlled in laboratory tests by means of compaction effort and seepage through the embankment body, respectively. The dynamic compaction technique employed in the preliminary experimental phase was refined to represent a more realistic method. A novel method was thus designed to simulate the construction of a real-size prototype embankment, where a vibratory and static load was used to apply and control, respectively, the compaction effort. The hydraulic aspects of the embankment breach mechanism were also investigated. For the first time, scale series tests have been used to assess the Froude criterion using tilted and quasi-exact geometric scales under very low inflow within the scope of three-dimensional breach overtopping. Data measurements included a time-history of water surface levels and video footage captured from three locations: upstream, downstream and above the embankment models. The analysis for the spatial breach overtopping tests involved measurement of the breach outflow hydrograph and breach channel evolution at the upstream slope, using hydrologic routing and a developed photogrammetric technique using the video footage, respectively. An expression which estimates the breach outflow based on this apparent upstream control section was therefore derived. The relationship between the measured and estimated breach outflow was expressed in terms of breach discharge efficiency. The third phase of the experimental program was comprised of two-dimensional overtopping tests to investigate the erodibility of a steep slope in overtopped noncohesive embankment models. A novel experimental two-dimensional configuration used to measure the pore-water-pressures within the embankment model body was developed using micro and standard tensiometer-transducer-probe assemblies, designed, assembled and tested at the Geotechnical Engineering Laboratory. A transient flownet analysis was developed using ArcGIS and the time-history of the pore-water-pressure measurements. All flow parameters were computed using the free water surface and bed profiles captured using a photogrammetric technique and the developed hydrologic routing method. Using the one-dimensional Saint-Venant equations, an analytical expression for the bed shear stress was derived to take into account the effects of unsteady flow, boundary seepage and steep slopes. Using the measured erosion rates and the sediment continuity principle, the bed mobility relationship expressed by the Shields and transport parameters was revisited to account for the effects of unsteady and supercritical flow on a downstream steep slope in the presence of boundary seepage. This novel transient flownet approach will lead to the development of new sediment mobility relationships for breach flows, instead of the classical sediment transport-capacity formulations which are based on steady, subcritical and normal flow conditions.

Earthen dams are often built into bedrock abutments and on bedrock foundations. Bedrock joints naturally occur in bedrock materials. These bedrock joints create voids for ground water to pass through. Historically earthen dams were sometimes built in direct contact with the bedrock joints, causing a contact point between the soil of the dam and the flowing water. It has been engineering practice to place grout into exposed bedrock joints for some time now. However, soil is not always cleaned out of bedrock joints before they are grouted, which leaves a weakness for water to push through. The purpose of this study is to understand the point at which water flowing through bedrock joints will erode soil from the earthen dam embankment. The information of how much soil is eroded away in an amount of time is also crucial to the scope of this study. The goals of this study were accomplished by building a physical model or apparatus of an earthen dam embankment on top of a simulated bedrock joint. Different soil types were tested in the apparatus to start a database of information about erosion rates of the soil along the bedrock joint and embankment interface. These results will be used to start a database for organizations that assign probabilities of dam failures. The purpose of the study is not to indicate when dams will fail, but to help with assigning probabilities of the likelihood of a serious problem being caused from this type of mechanism presented in this study.

Despite 'modern' construction and management techniques, flood embankment and embankment dam failures occur almost routinely around the world. The need to understand, predict and prevent the breaching process remains a high priority for owners and flood risk managers alike. This research provides new understanding and improved methods for predicting breach initiation and growth through earth flood embankments or dams. The improvement of breach model accuracy has made slow progress over the past 20 years, with confusion around breaching processes arising from a lack of appreciation of soil mechanics interacting with hydraulics and structural behaviour. The prediction of different breach processes requires the integration of techniques from all three disciplines. This thesis makes advances from earlier work (Mohamed, 2002) to produce a predictive breach model intended for industry application. The research develops improved approaches for flow calculation, sediment erosion and structural response for predicting breach initiation and growth and uses field data, including video footage, from the EU IMP ACT project and large scale test and case study data from collaboration with the International Dam Safety Interest Group breach modelling project.

In this thesis, some aspects concerning building embankments founded on sulphide clay are studied, with special reference to ground improvement by preloading in combination with prefabricated vertical drains (PVD’s). The main purpose of the research was to increase empirical knowledge of the mechanical behaviour of sulphide clays subjected to embankment loadings and of the interaction between vertical drains and sulphide clays. Important aspects related to ground improvement with PVD’s in more general terms are also treated, in particular how various uncertainties regarding the properties of the clay and the clay-drain interaction imposed in the design phase can be addressed. The benefits of using theobservational method for handling these uncertainties are discussed, and a description of how the method was used in an embankment project is presented. The results from the research are presented in one conference paper and two papers submitted to peer-reviewed international journals, which are appended. The design of PVD’s involves describing the consolidation characteristics of the clay and the interaction between the drains and the clay. Primarily, the rate of consolidation is determined by the hydraulic conductivity (permeability) of the clay in the horizontal direction. Hence, accurate determination of this material property is of paramount importance in making reliable design predictions. As conventional laboratory tests for assessing the consolidation characteristics of a clay only provide information about its properties in the vertical direction, one is often left to make assumptions about the horizontal properties based on empirical correlations. Reliable empirical knowledge of these correlations for a certain clay is there forevital. A large number of CRS tests were performed on horizontal and vertical samples ofsulphide clay in order to investigate the correlation between the horizontal and verticalhydraulic conductivity and coefficient of consolidation. The results show that there is very small anisotropy in these parameters and that the scatters in the results are large. For designpurposes, sulphide clays should therefore be assumed to be isotropic in this respect. In orde rto handle the variation in properties, several parallel tests should be made and partial factors of safety should be introduced in the design. Introducing partial factors of safety in the design of PVD’s is one of the main topics suggested for further research. Regarding the clay-drain interaction, a study of the disturbance effects (smear effects) during the installation of drains in sulphide clays was performed. Back-calculations of measurements of pore pressure dissipation were made via a parameter study. It was shown that smear affects the consolidation rate to some extent but that the natural (undisturbed) hydraulic conductivity is more significant. The undrained shear strength su of a clay is dependent on the preconsolidation pressure σ 'p . As the clay consolidates under a loading, the effective stress increases, possibly to magnitudes surpassing the initial preconsolidation pressure and thereby leading to increased undrainedshear strength of the clay. The relation between su and σ 'p, i.e. the ratio su /σ 'p for asulphide clay, was investigated based on results from a large number of in situ tests andlaboratory tests. There were large scatters in the measurements, but su /σ 'p =0.25 is suggested as being relevant in the direct shear zone for design purposes in sulphide clays.

QC 20101101

The construction of motorways in Slovakia faces a series of geotechnical problems due to the mountainous relief. One of these problems is also discussed in this diploma thesis, where the motorway route is led through a landslide area. The aim of the thesis is to compare two different proposals of the D1 motorway in part of Hubova - Ivachnova section. The theoretical part deals with the issue of slope movements in connection with transport line constructions. In the practical part, the proposals for specific solutions of the high embankment route variant and variant with the bridge are discussed. Both variants are designed in the Plaxis numeric program. Subsequent comparison and evaluation of variants is performed in relation to the degree of stability, deformation, structural stress and construction costs.

Les fuites au travers des ouvrages hydrauliques en remblai sont les signes précurseurs d'un dysfonctionnementdu dispositif d'étanchéité de l'ouvrage pouvant entraîner leur rupture. La détectionprécoce des fuites et leur quanti_cation est donc primordiale.Les méthodes géophysiques et thermométriques à grand rendement apportent des éléments deréponse pour la détection des fuites, le long des ouvrages à long linéaire, mais l'estimation de leurvitesse, nécessaire à l'évaluation de la dangerosité des fuites, n'est pas encore satisfaisante.Cette étude porte sur la détection et quanti_cation des fuites à travers les ouvrages hydrauliquesen remblai soumis à une charge d'eau permanente. Les méthodes proposées exploitent des mesures detempératures naturelles du sol à l'aide de _bres optiques placées sous le talus amont ou aval.Deux modèles de quanti_cation ont été développés et testés sur les données d'un site expérimentalcontrôlé et d'un site réel. Les résultats obtenus concordent avec les mesures de vitesse e_ectuées surles deux sites.

This master’s thesis deals with the feasibility study of the pumped-storage hydropower plant. Design is divided at three parts – upper water-reservoir with water intake, penstock with cabel tunnel and mechanical room with four Francis reversible turbine. Study contains engineering report, hydraulic calculations, photodocumentation and drawing documentation.

Conception de cette structure par le laboratoire central des ponts et chaussées afin d'étudier expérimentalement le comportement de ce type d'ouvrage. Détermination des efforts internes dans le mur à l'aide de capteurs intégrés à la structure et étude du mécanisme de leur fonctionnement par des calculs aux éléments finis tridimensionnels, puis par photoélasticimétrie. On passe des mesures de déformation aux efforts internes dans la structure par des formules de régression linéaire qui résultent de l'analyse statistique d'un grand nombre de cas d'étalonnage sous sollicitations contrôlés. Détermination théorique des dimensions optimales à donner au remblai pour que les efforts dans le mur soient représentatifs d'un massif d'extension semi-infinie. L'étude est effectuée par un modèle numérique bidimensionnel aux éléments finis et également par des calculs bidimensionnels à l'aide d'un logiciel, utilisant également les éléments finis. Analyse des premiers essais réalisés à la station.

Une formation marneuse, nommée "Terres Noires". se rencontre fréquemment dans presque tout le secteur sud-est de la France.La recherche a visé à approfondir la connaissance des caractéristiques géotechniques des Terres Noires saines ou altérées, de trois régions différentes. le Trièves. la fenêtre de Barcelonnette et le bassin de Draix. Les essais d'identification classiques, comme limites d'Atterberg, granulométrie ..... ,. mais aussi des techniques plus fines (microscope électronique à balayage) ont été mis en oeuvre. Il en résulte qu'à part une différenciation minéralogique, les Terres Noires des trois secteurs étudiés peuvent être considérées comme un ensemble lithologique homogène dont les différences de comportement sont essentiellement liées à leur teneur en carbonate et à leur texture microscopique. L'étude de l'utilisation des Terres Noires en remblai routier a aussi été effectuée en recourant à une série d'essais physiques et mécaniques. On en conclut que les matériaux extraits se prêtent à cet emploi, à la condition d'user de précautions particulières.

Levees are earth structures used for flood protection. Due to their easy availability and low permeability, clays are the most common material used for the construction of levees. Clays are susceptible to desiccation cracks when subjected to long dry spells during summers. There has been an increased interest in studying the occurrence of cracks in soil mass. In particular, many experimental investigations for soils have been undertaken to learn about the crack pattern in earth embankment. However, there is a dearth of work that focuses on the numerical modeling of desiccation cracks effects on levees. This study has been undertaken to analyze the effect of desiccation cracking on the hydraulic behavior of an earth embankment under flooding conditions. A numerical model was developed using the finite element package CODE_BRIGHT. The model was validated from the data obtained from a small scale embankment experiment under controlled environmental conditions. As the phenomenon of desiccation cracking is highly random, a simple random model was developed to capture the variability in crack geometry. The random crack geometry was then passed on to the finite element mesh, so that a probabilistic analysis can be carried out using a Monte Carlo approach, for assessing the embankment’s integrity. The results obtained from the analysis such as time to steady state saturation and steady state flow rate at the outward slope were very interesting to study and provided an insight on the effect of desiccation cracks on unsaturated earth embankments.

This dissertation describes the development of a finite element program for the analysis of conventional and reinforced embankments. The results of the program are verified with the field measurements of three full scale test sections constructed on soft soils. A parametric study is performed to investigate the effect of various components of a reinforced embankment on its behavior A finite element program was modified to include new finite elements and material models for soil, reinforcement, and interface. The program is now capable of modeling embankments under undrained, drained, and consolidation conditions. A creep inclusive elasto-plastic stress-strain model is used to represent the plastic behavior of soils and a hyperbolic stress-strain model is used to model the behavior of soils under nonlinear elastic conditions. The interface between the soil and the reinforcement is modeled by isoparametric joint elements with no thickness. The stress-strain model of the interface is also based on a hyperbolic stress-strain model. The reinforcement is modeled by isoparametric bar elements capable of transmitting axial forces through a linear stress-strain relationship The results of the finite element analyses agree with the field measurements of horizontal displacement, vertical displacement, forces, and pore pressure. The results of the parametric study indicate that the reinforcement strength has a major influence on reducing horizontal displacement, whereas the effect of the shear stiffness and the interface condition is relatively modest. The increase in the soil stiffness reduces the horizontal displacement significantly in both the foundation soil and the embankment. Accurate estimation of the coefficients of permeability is essential for predicting the horizontal displacement in the foundation soil and the tensile force in the reinforcement even for short term analysis. The bottom boundary of a finite element mesh of an earth embankment should be placed at a depth of twice the height of the embankment, whereas the lateral boundaries of the mesh should be at a distance of twice the depth of the foundation soil to eliminate the effect of the boundary conditions on the results of the analysis
acase@tulane.edu

碩士
國立高雄第一科技大學
營建工程所
95
The application of reinforced earth embankment in mountain areas is easily restricted by available space. It raises difficulty for allocating length of reinforcement. If we add soil nails on the back side of reinforced earth embankment, the soil nails could provide extra force as compensation for the lack of sufficient length of reinforcement embankment. This paper analyze applications of reinforced embankment system for different geometric slopes via the Limit Equilibrium Analysis computer program – ReSSA. Deduce length of reinforcement from safe factors of research result. In addition, Compound Construction Method combined soil nails and reinforcement retaining structure has been proven to be highly feasible. In order to solve the problem of mentioned above in mountain areas, this paper also uses the Compound Construction Method to design, and analysis via Finite Element Method program – PLAXIS. The geometric conditions of reinforced earth embankment include: (1) height of reinforcement earth embankment; (2) angle of reinforcement slope; (3) length of reinforcement material. Besides, this paper also has an emphasis on different weight loadings, both in static and dynamic states, on reinforced embankment. In order to build design chart of soil nail force for Reinforced Earth Embankments Reinforced by Soil Nails system as a basis. For different geometric conditions, this paper takes 7 meters, 9 meters, and 12 meters height into consideration. The result shows that the higher the embankment, the more tensile force the soil nails endures. As for the angle of embankment slope, we study it under 60 degree, 70 degree, 80 degree, and 90 degree, and find that the steeper the reinforced embankment, the more tensile force the soil nails takes. Besides, the angle of reinforcement slope influences tensile force distribution from each step of soil nails. While above one-third of embankment height, the bigger the angle of embankment slope, the more tensile force the soil nails takes; surprisingly, while below one-third of embankment height, the bigger the angle of embankment slope, the less tensile force the soil nails sustains. As for the length of reinforced materials, the longer the reinforced materials, the less the maximum tensile force of soil nails bears. Moreover, this paper studies friction angle of backfill in 25 degree, 30 degree, and 35 degree, to understand influences on stability of reinforced area from different backfill. The result shows when the friction angle of backfill is higher, reinforced earth embankment maintains higher stability and soil nails endure less tensile force. For mastering the tensile force needed from soil nails in different geometric conditions, this paper categorizes results of mechanics analysis from reinforced earth embankment connected with soil nails under static weight loadings in different geometric conditions, and establishes design chart of tensile force from soil nail to normalize the maximum tensile force.

碩士
國立成功大學
土木工程學系碩博士班
94
The two dimensional finite difference software FLAC(Fast Largragian Analysis of Continua), is adopted to simulate the dynamic behavior of a reinforced earth embankment of “Shaking Table Test” which established by Adam Perez(1999)in University of Washington USA; the hyperbolic soil model established by Duncan and Chang is used to modify the soil modului under different confined compressions. The numerical model of the reinforced earth embankment is improved by placing a sand layer of 3 cm thickness above the last layer of reinforcement material. It may reduce the sliding effect in the last layer of reinforcement usually occurred in the field.　 　　The results of study indicated that as the strength of the reinforcement increase on the spacing of the reinforcement decrease, the behavior of the embankment turn integrating as the embankment under dynamic conditions the bulge of soil may be generated at the back of the embankment. It also found that the yielding rate of the reinforced embankment increases as the strength of the reinforment on the embedded length of the embankment increases; however, the yielding are may decrease as increase of the spacing of the reinforcement.

碩士
國立高雄第一科技大學
營建工程所
95
In traditional and ancient Taiwan, using the balance method of dig and embankment to build the hill road owing to the poor conditions of topograohy, and the RC wall structure as the road foundation, breaks the stability of hillside. When the typhoon or heavy rain coming, the poor drainage inducing the collapse of road foundation and damage road to bring some negative effects of permanent usage. The recovery of the collapsed mountainous roadways usually worked in the condition of limit space of road dike. When choosing the ecological reinforced road dike structure method has the advantage of low environmental impaction and work fast, while due to the insufficient length of material extension causes the reinforced road dike not to maintain the stability. To improve the disadvantage, if add the soil-nail in the back side to strengthen stratum and can increase the road dike stability, and planting in the slope surface according the ecological engineering demand after the work finished. The reinforced road dike connected soil-nail structure is a complex system work method, and the safety has been confirmed by theory to some extent. By the field static loading and traffic loading test used in the reinforced mountainous roadways dike system, to verify the tensile resistance of the reinforced grid-net and steel rope connected system and the safety of being forced soil-nail. On the safety of stability condition and focus on the repair of the collapsed road dike, and on the impaction of environmental landscape, economic, work-period, and the ease or hard in work, to assess and discuss the possibility of reinforced road dike method to use in the hill-road and offer the reference to the government of the repair of collapsed road dike in the hill area.

碩士
中興大學
土木工程學系所
95
The primary purpose of instrumentation is to provide data to evaluate the safety of embankment dam by obtaining quantitative data on its performance, and to detect problems at an early and preventable stage. Instrumentation data should establish warning levels to indicate an acceptable level of performance for the dam during the first impounding and long-term operation. This study use Liyutan earth dam as a case basing on potential failure mode concept to establish warning levels. According to design data and historic events, there are three potential failure modes in this dam, dam seepage, core pore-water pressure, settlement and horizontal (longitudinal and transversal direction) movement are the key instruments. As the result of analysis and discussion, Liyutan dam seepage is categories into wet period and dry period, wet period is affected by rain down factor seriously, dry period is not. Flow-net graphical, theoretical and statistical methods is suit for evaluation seepage warning level in dry period, figuring method is suit for wet period. Theoretical analysis of pore-water pressure is not concord with actual measurements; it may be affected by instrumental error or influence permeability coefficient different from theories value .It is proposed to use statistical analysis method of actual measurements to evaluate warning level of pore-water pressure. The Limit value of dam deformation can be decided by theoretical analysis, warning level of dam deformation could be evaluated from experience value and actual measurements.

碩士
國立屏東科技大學
水土保持系所
95
Under the construction of the earth dam (embankment) in the mudstone area of soutern-west of Taiwan, due to the special foundation and climate, there is barely sign of vegetation. And the soil erosion is very serious. The human lives and belongs undergo great threatening. Thus in the research, we collect the fundamental data of the earth dam (embankment) through on-spot investigation, accompanied with erosion observation and handy dynamic cone penetrion test, in order to judge the basic type of soil and analyze the degree of damage. After that, in the laboratory, we adopt the method of SCD Test in Direct shear test to gain the parameter of soil dynamics, and later try to define the leaking line of the earth dam. We also use the software for slope stability analysisto evaluate the stability of the dam (embankment). After cross-examining the results from slope stability analysis and handy dynamic cone penetrion test, we gain the conclusion as follows: 1. According to the survey of earth dike in south-west Taiwan mudstone area, we found out that most of the dikes do not follow the requirement of soil-and-water conservation brochure. Though the height of construction is far lower than restricted, it still caused great damage for it has exceeded the set restriction, such as the excess of front and lower side slopes and height of breakwater from S.W.L. 2. As for the factors to damage, the structure of the earth dike we investigate is simple and the Self-Weightis little so that it does little impact on the substratum. Thus there are no such problems as piping, sinking, sliding and insufficient bearing capacity of the dam base, which are caused by the unsteady substratum. As for the imperfection of the earth dam itself, some commonly seen problems are the erosion, leaking and the slide of the surface slope. These problems often result in serious damage. 3. By handy dynamic cone penetrion test, we could check the inner part of the dam is composed with homogeneous soil or not, in order to use Nc to distinguish the weakest parts inside the dam. 4. The position of weak surface in the inner structure of the dam could differ by the geometric types and soil variables. On the influence of seepage, the intensity of the soil foundation might be slightly different. If the area of the weakest Nc is too close to the ground surface, it is likely to be less stable for the influence of the seepage to the slope. In consequence, to reduce seepage efficiently could strengthen the stability of the slope. 5. The stability analysis could identify the stability of the earth dam (embankment). If accompanied with handy dynamic cone penetrion test, the ultimate outcome would be the more precise and pointed.

Les infrastructures de transport est essentielle au maintien et à l'expansion des activités sociales et économiques dans les régions circumpolaires. À mesure que le climat se réchauffe, la dégradation du pergélisol sous les remblais a entraîné de graves dommages structuraux à la route, entraînant une augmentation importante des coûts d'entretien et une réduction de la durée de vie des infrastructures. Pendant ce temps, l'advection de chaleur déclenchée par les écoulements d’eau souterrains peut altérer le bilan énergétique du remblai et du pergélisol sous-jacent et modifier le régime thermique des remblais routiers. Cependant, peu de recherches ont été effectuées pour comprendre la synergie entre les processus thermiques de surface et souterrains des remblais routiers des régions froides. L'objectif de cette recherche était de comprendre les interactions thermiques entre l'atmosphère, le remblai routier, les écoulements d’eau et le pergélisol dans le contexte du changement climatique. Cette base, de connaissances est nécessaire pour la conception technique, l'entretien des routes et l'évaluation de la vulnérabilité des infrastructures. Les travaux de recherche ont permis de développer de nouvelles méthodes d'analyse thermique pour caractériser et identifier le rôle de l'advection thermique sur le changement de température d'un remblai routier expérimental au Yukon (Canada) en termes d’intensité, de vitesse et de profondeur de l'impact thermique. Les résultats montrent que l'augmentation de la température due aux flux de chaleur advectifs déclenchés par l’écoulement d'eau peut être jusqu'à deux ordres de grandeur plus rapide qu'en raison du seul réchauffement atmosphérique. La recherche a ensuite présenté un bilan énergétique de surface pour quantifier la quantité d'énergie entrant dans le centre et la pente du remblai avec des épaisseurs et des propriétés de neige variables. Le tout a été appuyé par des observations géothermique de plusieurs années et une grande quantité de données météorologiques. Les résultats illustrent que le bilan énergétique de surface est principalement contrôlé par le rayonnement net et moins par le flux de chaleur sensible. Le flux de chaleur transmis à la pente du remblai diminue de façon exponentielle avec l'augmentation de l'épaisseur de la neige et diminue de façon linéaire avec l’installation du couvert de neige et la longueur de la période d’enneigement. De plus, un modèle de bilan énergétique de surface et un modèle cryohydrologique entièrement couplé ont été développés pour étudier l'impact thermique de l'advection de chaleur associée à l'écoulement de l'eau souterraine sur le dégel du pergélisol et le développement de taliks (c.-à-d. zone perpétuellement non gelée dans les zones de pergélisol). Le modèle couplé a réussi à reproduire la tendance à la hausse du plafond du pergélisol (erreur absolue moyenne <0,2 m) au cours de la période 1997-2018. Les résultats montrent que l'advection de chaleur a fourni une source d'énergie supplémentaire pour accélérer le dégel du pergélisol et a doublé le taux d’augmentation de l’épaisseur de la couche active 0,1 m·a-1 à 0,19 m·a-1, par rapport au scénario où aucun écoulement d'eau ne se produit. Le talik s'est initialement formé et développé en fonction du temps sous l’effet combiné des écoulement d’eau, de l'isolation de la neige, de la construction de la route et du réchauffement climatique. Le débit d'eau souterraine a relié des corps isolés de talik et a amené le remblai de la route dans un état thermique irréversible, en raison de la rétroaction de l'eau liquide (effet de chaleur latente) piégée dans le talik. Ces résultats montrent l'importance de l'advection de chaleur induite par l'écoulement d'eau sur le régime thermique de la sous-couche (c.-à-d. la couche de matériau de remblai) et du sous-sol (c.-à-d. le matériau natif sous un remblai) du remblai lorsque le remblai routier intercepte le drainage local. De plus, les résultats obtenus soulignent la nécessité de coupler les processus thermiques de surface et souterrains dans le but d'évaluer la stabilité thermique des routes subarctiques.
Transportation infrastructure is crucial to maintaining and expanding the social and economic activities in circumpolar regions. As the climate warms, degradation of the permafrost causes severe structural damages to the road embankment, leading to large increases in maintenance costs and reductions in its lifespan. Meanwhile, heat advection triggered by mobile water flow can alter energy balance of the embankment and underlying permafrost and modify the thermal regime of road embankments. However, little research has been done to understand the synergy between surface and subsurface thermal processes of cold region road embankments. The overall goal of this research was to elucidate thermal interactions between the atmosphere, the road embankment, mobile water flow, and permafrost within the context of climate change. This knowledge is needed for engineered design, road maintenance, and infrastructure vulnerability assessment. The research first used new thermal analysis to characterize and identify the role of heat advection on temperature change of an experimental road embankment, Yukon, Canada in terms of magnitude, rate and thermal impact depth. It shows that soil temperature increase due to advective heat fluxes triggered by mobile water flow can be up to two orders of magnitude faster than due to atmospheric warming only. The research then presented a novel surface energy balance to quantify the amount of ground heat flux entering the embankment center and slope with varying snow depth and properties, supported by multi-year thermal and meteorological observations. My results illustrate that the surface energy budget is mainly controlled by net radiation, and less by the sensible heat flux. The ground heat flux released at embankment slope exponentially decreased with the increase of snow depth, and was linearly reduced with earlier snow cover and longer snow-covered period. A fully integrated surface energy balance and cryohydrogeological model was implemented to investigate the thermal impact of heat advection associated with subsurface water flow on permafrost thaw and talik (i.e., perennially unfrozen zone in permafrost areas) development. The integrated model successfully reproduced the observed increasing trend of the active layer depth (mean absolute error < 0.2 m) over the 1997-2018 period. The results show that heat advection provided an additional energy source to expedite permafrost thaw, doubling the increasing rate of permafrost table depth from 0.1 m·a-1 to 0.19 m·a-1, compared with the scenario where no water flow occurs. Talik formation and development occurred over time under the combined effect of subsurface water flow, snow insulation, road construction and climate warming. Subsurface water flow connected isolated talik bodies and triggered an irreversible thermal state for the road embankment, due to a local feedback mechanism (latent heat effect) of trapped, unfrozen water in talik. These findings elucidate the importance of heat advection induced by mobile water flow on the thermal regime of embankment subbase (i.e., a layer of fill material) and subgrade (i.e., the native material under an embankment) when the road embankment intercepts the local drainage. Furthermore, the obtained results emphasize the need to couple surface and subsurface thermal processes to evaluate the thermal stability of sub-Arctic roads.