The objective of this study is to provide a better understanding of suffusion characteristics of glacial soils and to present a simple yet reliable assessment procedure for determination of suffusion in the laboratory.Internal erosion by suffusion occurs in the core of an embankment dam when the ability of the soil to resist seepage forces is exceeded and voids are large enough to allow the transport of fine particles through the pores. Soils susceptible to suffusion are described as internally unstable. dams with core of broadly graded glacial moraines (tills) exhibit signs of internal erosion to a larger extent than dams constructed with other types of materials.The Suffusion behavior of glacial soils has been investigated through two different permeameter suffusion test have been employed, small scale permeameter and big scale permeameter. Details of the equipment along with its calibration, testing and sampling procedures are provided.The testing program were performed 9 test with different compaction degree in small scale permeameter and 2 test in big permeameter on internally stable categories of till soil. The categories are defined based on the soil grain size distribution and according to the methods developed by Kenney & Lau and Burenkova.Layers are identified with suffusion if the post-test gradation curve exhibit changes in distribution compared to the initial condition and also the tests revealed that the effect of grain size distribution and relative degree of compaction on the internal erosion susceptibility of glacial till soils at different hydraulic gradients

Numerical analyses of two different geotechnical problems, namely a bridge abutment and a geosynthetic reinforced embankment are presented in this thesis. Settlement, bearing capacity and slope stability are the major factors that need to be considered in the design of a foundation near a sloped fill. In this thesis, the behaviour of a small scale model footing located near the shoulder of a sloped fill was investigated numerically. Single and multiple layers of geogrid were used to reinforce the sloped fill, and their effects on the load-deformation behaviour and bearing capacity of the footing were explored. The analyses showed 80%, 168%, 295% and 375% maximum improvement in the ultimate bearing capacity with 1, 2, 3 and 4 reinforcement layers respectively. This maximum improvement depends on the embedment depths of the reinforcement layers below the foundation and the suggested optimal depths are discussed. Typically, greatest improvement in ultimate bearing capacity with a single layer of reinforcement was obtained when the reinforcement was at a depth between 0.50 and 0.75 times the foundation width. Similarly, highest ultimate bearing capacity with 2 reinforcement layers was predicted when the spacing between them was 1.0 times the width of the foundation. However, higher settlement was estimated at failure for the reinforced sloped fill than the unreinforced one. The second problem investigated was the three-dimensional (3D) analysis of Sackville embankment, a geosynthetic reinforced embankment on soft soil. Previous analyses using two-dimensional (2D) numerical modelling of Sackville embankment indicated potential 3D effects affecting the performance of this embankment. Therefore, 3D analysis incorporating geometric variations of Sackville embankment foundation soil, anisotropic model for fluid flow, mobilization of geotextile stresses in minor direction and the boundary effects (lateral directions) were taken into account in this analysis. The predicted performance of Sackville embankment were compared with the field data and the previously reported 2D analysis results in terms of vertical and horizontal displacements and excess pore pressures in the foundation soil, and geotextile stresses, strains and displacements. Better overall predictions of the Sackville embankment performance was obtained from this 3D analysis than the previous analysis reported in the literature.

The mainline railway track between Dublin and Belfast in Northern Ireland was constructed during the 1850's. Substantial lengths of railway embankment were constructed over poor-quality peaty soils. This was accomplished using tree trunk fascines placed directly on the natural ground surface; with poor-quality local peaty soils used as light weight fill.<p>In recent years, Northern Ireland Railways have noticed that these sections of railway track have been deteriorating more rapidly than sections of the track where the foundations are more competent. The magnitudes of displacement of the track under train loading appear to be increasing gradually over time and train speeds have had to be reduced.<p>This thesis is based on the research done to monitor the response of these railway track and embankment structures to dynamic train loading. The displacements were monitored for two different embankments under a variety of loading conditions and for various seasonal conditions. These displacements were recorded using a sensor created for this task. The sensor consisted of a photo-sensitive array mounted on the sleepers and a laser, which was placed outside the area of influence of train loading, and shone on the photo-sensitive array. <p>Analytical (Winkler) modelling was conducted to determine the effects of train speed and the cause of the large train-induced displacements. Analytical and finite element modelling were used to determine the effectiveness of alternative methods of embankment stabilization.<p>The results from the analytical modelling suggest that the deformation of the embankment under train loading was not due to dynamic excitation, but static deformation of the poor-quality fill and soft foundation materials. From both the analytical and finite element modelling of possible remediation techniques, methods that stiffen the embankment and foundation material are shown to be the most effective at reducing the train induced deflection of the embankment.

The stability of railway embankment is essential for safe transport. In order to ensure safe transport, water should be allowed to freely drain. Furthermore, as the engine driver has to be able to see signs, and people working on the embankment are supposed to easily see flaws on the rails to ensure safety for the passing trains, plants should not be allowed to grow on the embankment. In Sweden there are 12 000 kilometers of railway tracks and 25–30 % of them are treated for weed control every year. The Swedish Transport Administration is currently using the pesticide “Roundup Bio” to remove weeds on the embankment. To prevent the dispersal of chemicals to sensitive ecosystems, chemical transport has to be investigated carefully. In this master thesis a transport model for the transport of pesticides has been simulated using the software “GoldSim”. The model have been developed, optimized and controlled by a sensitivity analysis. In addition to this an analysis of worst case scenarios has been tested. The pesticides “Arsenal 250” with the active substance imazapyr and “Roundup Bio” with the active substance glyphosate have been used in the calibrating of the model. The transport model for imazapyr shows a good estimation of the mass of herbicides in the embankment compared to measurements. There is also a good estimation in the groundwater even if the concentration at the beginning of the simulation period is underestimated. The simulation with glyphosate, on the on the other hand, showed very small quantities of both glyphosate and its degradation product AMPA (aminometylphosphateacid) in both the embankment and in the groundwater. The sensitivity test showed that the parameter half-life and Kd-value (adsorption capacity) were the most sensitive parameters in the model. When it comes to the concentration in the groundwater the distance to the groundwater level was the most sensitive parameter, as well as the Kd-value in the embankment, the half-life and the precipitation. As expected, the worst-case analysis showed that a small distance to the groundwater level, a low Kd-value and a short half-life produced even larger concentrations of herbicides in the groundwater. In conclusion it should be mentioned that the stimulation model generally works well in regards to with imazapyr. For stimulation of glyphosate and its metabolite AMPA more work with the model is required for the Swedish Transport Administration to apply it in the future.

The mainline railway track between Dublin and Belfast in Northern Ireland was constructed during the 1850's. Substantial lengths of railway embankment were constructed over poor-quality peaty soils. This was accomplished using tree trunk fascines placed directly on the natural ground surface; with poor-quality local peaty soils used as light weight fill.<p>In recent years, Northern Ireland Railways have noticed that these sections of railway track have been deteriorating more rapidly than sections of the track where the foundations are more competent. The magnitudes of displacement of the track under train loading appear to be increasing gradually over time and train speeds have had to be reduced.<p>This thesis is based on the research done to monitor the response of these railway track and embankment structures to dynamic train loading. The displacements were monitored for two different embankments under a variety of loading conditions and for various seasonal conditions. These displacements were recorded using a sensor created for this task. The sensor consisted of a photo-sensitive array mounted on the sleepers and a laser, which was placed outside the area of influence of train loading, and shone on the photo-sensitive array. <p>Analytical (Winkler) modelling was conducted to determine the effects of train speed and the cause of the large train-induced displacements. Analytical and finite element modelling were used to determine the effectiveness of alternative methods of embankment stabilization.<p>The results from the analytical modelling suggest that the deformation of the embankment under train loading was not due to dynamic excitation, but static deformation of the poor-quality fill and soft foundation materials. From both the analytical and finite element modelling of possible remediation techniques, methods that stiffen the embankment and foundation material are shown to be the most effective at reducing the train induced deflection of the embankment.

Roads and highways in cold regions are negatively affected by settlement of embankments in areas of degraded or degrading permafrost, particularly in areas with mean annual temperatures close to 0°C where permafrost is locally discontinuous. Climate warming and human activities can lead to increases in the temperature of permafrost and to thawing. In regions of discontinuous permafrost, thawing may produce thickening of the active layer, large settlements and non-recoverable shear deformations. These can cause potentially dangerous trafficability issues. The research program involved a test site on Provincial Road PR391, about 18 km northwest of Thompson, Manitoba. The foundation material of PR391 is currently classified as “degraded (thawed) permafrost”. The purpose of this research was to investigate and understand the performance of highway embankments on thawed permafrost. The research involved field instrumentation and data collection, laboratory testing, thermal modelling and frost heave predictions. The results of the field instrumentation and data collection show net heat flow into the ground, as well as development of cyclic seasonal gradients of total head. This is believed to be a significant original contribution to understanding the effects of climate change on highway infrastructure. The results also show that displacements observed at the PR391 embankment are a combination of consolidation and shearing strain of the foundation material. Most studies of embankments concentrate on vertical settlements. This research shows that horizontal movements are also present, a contribution that helps explain the mechanism of lateral spreading. The results of the laboratory testing show that the mechanical and shearing properties of the soil collected from the PR391 embankment are not significantly affected by differences in temperature once water in the soil has actually thawed. The results of the thermal modelling show reasonable trends in simulated ground temperatures compared with the data obtained from the thermistors underneath the embankment. The frost heave prediction of PR391 shows that in situ frost heave characteristics can be estimated by applying the Segregation Potential (SP) frost heave method in field conditions. This provides a valuable field study to the limited number of such studies of Segregation Potential, which are normally done under laboratory conditions.

There is a growing need to improve the understanding of the behaviour of infrastructure in permafrost regions. Permafrost affects nearly half of the land surface in Canada, especially in the north. Further development of natural resources in northern Canada will provide socio-economic benefits to the region and its residents. Linear infrastructure, such as highways, is an important part of that development. The integrity of infrastructure in northern regions is negatively impacted by thawing and degradation of the underlying permafrost initiated by changes in both air and ground temperatures. Subsequent deformations due to settlement and lateral spreading can lead to potentially hazardous driving on highways. The author’s research focused on a section of highway embankment on Provincial Road (PR) 391 located 18 km north of Thompson, Manitoba. The purpose of the research was to further understanding of the thermal and deformation behaviour of an embankment subjected to degrading permafrost conditions. The author’s research consisted of laboratory testing, instrumentation installation, data monitoring, and numerical modelling. Laboratory tests on four-inch (101.6 mm) diameter Shelby tube samples characterized the soil at the site. Data were collected remotely via satellite, and included ground temperatures, pore water pressures, and displacements both laterally and vertically. Ground temperatures indicated a frost bulb, a region of frozen ground, under the embankment. Thermal models using TEMP/W simulated the current ground thermal regime and projections of future thermal behaviour of the embankment. Deformation numerical models using SIGMA/W incorporated changes in the size of the frost bulb over a freeze-thaw cycle to simulate the deformation behaviour of the embankment. The numerical models were compared with the collected data.

Roads and highways in cold regions are negatively affected by settlement of embankments in areas of degraded or degrading permafrost, particularly in areas with mean annual temperatures close to 0°C where permafrost is locally discontinuous. Climate warming and human activities can lead to increases in the temperature of permafrost and to thawing. In regions of discontinuous permafrost, thawing may produce thickening of the active layer, large settlements and non-recoverable shear deformations. These can cause potentially dangerous trafficability issues. The research program involved a test site on Provincial Road PR391, about 18 km northwest of Thompson, Manitoba. The foundation material of PR391 is currently classified as “degraded (thawed) permafrost”. The purpose of this research was to investigate and understand the performance of highway embankments on thawed permafrost. The research involved field instrumentation and data collection, laboratory testing, thermal modelling and frost heave predictions. The results of the field instrumentation and data collection show net heat flow into the ground, as well as development of cyclic seasonal gradients of total head. This is believed to be a significant original contribution to understanding the effects of climate change on highway infrastructure. The results also show that displacements observed at the PR391 embankment are a combination of consolidation and shearing strain of the foundation material. Most studies of embankments concentrate on vertical settlements. This research shows that horizontal movements are also present, a contribution that helps explain the mechanism of lateral spreading. The results of the laboratory testing show that the mechanical and shearing properties of the soil collected from the PR391 embankment are not significantly affected by differences in temperature once water in the soil has actually thawed. The results of the thermal modelling show reasonable trends in simulated ground temperatures compared with the data obtained from the thermistors underneath the embankment. The frost heave prediction of PR391 shows that in situ frost heave characteristics can be estimated by applying the Segregation Potential (SP) frost heave method in field conditions. This provides a valuable field study to the limited number of such studies of Segregation Potential, which are normally done under laboratory conditions.

Acid Sulphate Soils (ASS) often cause acidic pollution in canal water, which negatively impacts on water quality, biodiversity and the livelihood of farmers and fishermen, especially the landless poor. The problem is particularly acute in the coastal zones, where people already suffer from the consequences of salinity intrusion. Reducing acidic pollution is important for improving agricultural and aqua-cultural production and also the living conditions of people living in coastal zones with ASS. This study aims at developing an analytical tool that can simulate the propagation of acidic pollution and that would allow planers and managers to develop water management options and other resource management measures to reduce acidic pollution in the canal network of a coastal zone. / This study utilizes a systems approach, with a series of field, laboratory studies, in combination with statistical and GIS-based analyses and simulation modelling. Field and laboratory studies were carried out during 2001 - 2006 in Ca Mau peninsula, Mekong Delta, Vietnam, to fill in knowledge gaps on the source and amount of acidic loads from soil to the water surroundings, their interaction with saline water and their propagation in the canal network. Knowledge generated from this study was used in developing and validating a model to simulate the propagation of acidity in the tidal canal network with brackish water. / Measured data showed that the acidic pollution in the canal network varies seasonally. The pH of the canal water was lowest (3 – 4.5) at the beginning of the rainy season and highest (7 – 7.5) at the end of the rainy season and during the dry season. The reduced dredging activities in year 2005 and 2006 may explain why the acidic pollution decreased in 2005 – 2006 compared with 2001 –2004. The most serious acidic pollution occurs when the two following conditions are present simultaneously: (i) The existence of newly dredged canals (and hence the deposition of the excavated spoils on the canal embankment) in areas with ASS (especially with a severe ASS); and (ii) little or a lack of water exchange from tidal flows. Field experiments showed that ASS embankments within 2-3 years after dredging represent a high acidity hazard because they can release into the canal a total acidity, mainly from runoff and seepage water, of up to 2.7 mol H+day-1 per meter length of canal embankment. Functional relationships were established allowing quantification of the daily acid load transferred from fields and canal embankments to the canal network. / A laboratory titration experiment showed that saline water could buffer the effects of acidic pollution in the canal water. A new ACIDITY module was developed and was coupled to an existing hydraulics and salinity model (the Vietnam River Systems And Plains - VRSAP). The model was calibrated with measured data from 2003 and validated with data from 2005. The Model is the first of its kind able to simulate the temporal and spatial dynamics of changes of pH (as an indicator of acidity) at a regional scale, together with salinity and water flow characteristics in a tidal canal network with brackish water. The Model can be used to investigate the effects of different scenarios of water and other resource management options on the extent of acidic pollution in a coastal area. Analysis of simulation runs for various scenarios indicate that opening the two main sluices along the East Sea at high tide in one day every week in May and June for saline water intake, combined with widening the canals that connect these sluices to the West Sea can eliminate the acidity problem in the study area. Large scale dredging of canals of ASS in fresh water zone should be avoided as it can create severe acidic pollution of the canal water.

Permettant de protéger les populations des inondations, de canaliser l'eau à des fins d'irrigation ou de production d'électricité, les digues en terre sont des ouvrages stratégiques dont la rupture peut avoir des conséquences dramatiques. La stabilité de ces ouvrages doit ainsi pouvoir être assurée, notamment en cas de séisme. Cependant, étant donné le très grand linéaire qu'ils représentent, la mise en œuvre de vastes campagnes de reconnaissances et de modèles numériques complexes n'est pas toujours envisageable dans les zones de sismicité modérée. L'utilisation d'outils simplifiés, faisant appel à des données facilement mesurables, se révèle indispensable pour fournir une indication sur la stabilité de tronçons de digue soumis à un chargement sismique. Les méthodes simplifiées existantes permettant d'estimer la réponse dynamique des remblais sont inadaptées au contexte des digues. En effet, alors que les digues sont pour la plupart construites dans des vallées sédimentaires, la majorité de ces méthodes, développées pour l’étude des barrages, supposent que l’ouvrage est fondé directement au rocher. Seules deux approches permettent de prendre en compte l’interaction entre l’ouvrage et son sol d’assise (effets de site) : la méthode de Sarma(1979) et celle de Papadimitriou(2014). Cependant, la première est basée sur des hypothèses très fortes (elle considère notamment un rocher rigide et un amortissement uniforme, qui plus est très fort) et la seconde se limite à des ouvrages ayant une hauteur supérieure à 20 si{m}. L'approche développée au cours de cette thèse repose sur des hypothèses plus réalistes, en considérant notamment des géométries adaptées à celles des digues, en prenant en compte les effets de site et en adaptant la dissipation d'énergie au niveau de sollicitation. Une étude paramétrique numérique (calcul de la réponse visco-élastique par éléments spectraux en deux dimensions) est utilisée pour couvrir un ensemble de configurations géométriques et mécaniques de digues. Pour prendre en compte la non-linéarité, les valeurs d'amortissement et de dégradation du module de cisaillement sont adaptées en chaque point des modèles à partir des résultats fournis par une série de calculs en linéaire équivalent 1D. Les réseaux de neurones artificiels, dont l'apprentissage est basé sur les résultats des simulations numériques, sont utilisés pour le développement d'une nouvelle méthode simplifiée. Des abaques sont réalisés, à partir des réseaux de neurones établis, pour offrir une alternative visuelle à leur utilisation "mathématiques". Les outils simplifiés auxquels aboutit cette thèse font appel à des paramètres facilement mesurables sur le terrain. Des méthodes géophysiques sont mises en œuvre au niveau de quatre sites de digues afin d'identifier le meilleur compromis de mesures permettant d'estimer les paramètres nécessaires à l'évaluation de la réponse dynamique de l'ouvrage. / Embankments are strategic facilities that, among other things, protect population from flooding and canalize rivers for energy production or for irrigation concerns. Since their rupture can lead to terrible consequences, they must remain stable, especially in case of earthquake. However, given the very large length of embankments, it is rarely possible to conduct complete investigations and complex numerical models in regions of moderate seismicity. Therefore, simplified tools to estimate the dynamic response of embankments using accessible embankments’ features are necessary to estimate their capacity to resist seismic loadings. Existing simplified methods, generally developed to assess the dynamic response of embankment-dams, turn out to be inappropriate to study the particular case of embankments along rivers – or other types of embankment, with small height and large length. The majority of these simplified methods do not take into account site effects: they assume the presence of rock directly at the base of the embankment, whereas most of large length embankments are located in alluvial valleys. Two methods only - Sarma(1979) and Papadimitriou(2014) - take into account the interaction between the embankment and its soil foundation. However, the first one relies on strong assumptions (among others, that the bedrock is considered rigid and that the viscous damping is supposed to be both spatially uniform and very large) and the second one is limited to tall embankments (higher than 20 si{m}).The method developed in this thesis relies on assumptions that are more realistic: it considers geometries adapted to large length embankments, it accounts for the presence of a soil foundation and includes an energy dissipation process consistent with expected levels of strain. A numerical parametric study is performed based on the computation with the spectral element method of the viscoelastic response of a large set of embankments spanning a wide range of geometrical and mechanical properties. In order to take into account nonlinearity, damping and shear modulus reduction are adapted in each point of the numerical models according to the results of a set of 1D linear equivalent computations. A new simplified method is derived from the obtained numerical results using artificial neural networks. Abacuses are produced from the neural networks so that engineers can have at their disposal a visual tool. This thesis leads to a simplified method that uses some accessible features of embankments as input parameters. The ability of classical geophysical methods to provide those input parameters is further estimated on four sites corresponding to different realistic configurations.