Showing papers in "Canadian Geotechnical Journal in 2011"
TL;DR: In this article, a numerical model is proposed to predict the future behavior of land subsidence in Shanghai due to pumping of groundwater, which takes into account the multi-aquifer-aquitard hydrogeological condition of the soft deposit of Shanghai.
Abstract: To predict the future behavior of land subsidence in Shanghai due to pumping of groundwater, a numerical model is established. In the proposed model, groundwater flow in three-dimensional conditions and soil deformation in one-dimen- sional conditions are calculated. The model takes into account the multi-aquifer-aquitard hydrogeological condition of the soft deposit of Shanghai. The variation of the coefficient of compressibility and coefficient of hydraulic conductivity of the soils with the consolidation process are simulated. Relationships among land subsidence, groundwater withdrawal volume, and groundwater level are analyzed. Comparison between the measured value and calculated value shows that the model simulates the measured value fairly well. The future of land subsidence behavior due to groundwater withdrawal is predicted and discussed via consideration of the variation of the following parameters in the future 30 years: net withdrawn volume of groundwater, pumping layer, and pumping region. Resume : Un modele numerique est propose afin de predire le comportement futur d'un affaissement de sol cause par le pompage de l'eau souterraine a Shanghai. Dans le modele propose, l'ecoulement de l'eau souterraine en trois dimensions et la deformation du sol en une dimension sont calcules. Le modele considere la condition hydrogeologique multi-aquifere- aquitard du depot mou de Shanghai. Les variations du coefficient de compressibilite et du coefficient de conductivite hy- draulique des sols lors du processus de consolidation sont simulees. Les relations entre l'affaissement du sol, le volume de retrait de l'eau souterraine et le niveau phreatique sont analysees. Des comparaisons entre les valeurs mesurees et calculees montrent que le modele peut simuler les valeurs mesurees relativement bien. Le comportement futur du sol en affaissement cause par le retrait de l'eau souterraine est predit et discute en considerant les variations pour les prochains 30 ans pour les parametres suivants : le volume net d'eau souterraine retire, la couche de pompage et la region de pompage. Mots-cles : pompage de l'eau souterraine, affaissement du sol, ecoulement de l'eau souterraine en trois dimensions, consoli- dation en une dimension, prediction. (Traduit par la Redaction)
309 citations
TL;DR: In this article, a Monte Carlo simulation (MCS)-based reliability analysis approach for slope stability problems was developed and utilizes an advanced MCS method called "subset simulation" for improving effi ciency.
Abstract: This paper develops a Monte Carlo simulation (MCS)-based reliability analysis approach for slope stability problems and utilizes an advanced MCS method called “subset simulation” for improving effi...
254 citations
TL;DR: In this paper, the authors performed permeameter tests on four widely graded cohesionless soils, to study their susceptibility to in- ternal erosion, and provided an insight into the spatial and temporal progression of seepage-induced internal instability.
Abstract: Permeameter tests were performed on four widely graded cohesionless soils, to study their susceptibility to in- ternal erosion. Test specimens were reconstituted as a saturated slurry, consolidated, and then subjected to multi-stage seepage flow under increasing hydraulic gradient. The occurrence of internal instability is described qualitatively, from vis- ual observations through the wall of the permeameter during a test and from post-test observations; it is also described quantitatively, from change of hydraulic gradient within the specimen and from axial displacement during a test. The re- sults provide a novel insight into the spatial and temporal progression of seepage-induced internal instability. This insight yields an improved characterization of suffusion and suffosion in cohesionless soils, the progression of which appears gov- erned by a critical combination of hydraulic gradient and effective stress. Resume´ : Des essais en permeametre ont eterealises sur quatre sols sans cohesion et agranulometrie etalee afin d'etudier leur susceptibilitea l'erosion interne. Les echantillons ont etereconstitues sous forme de pulpe saturee, consolidee et en- suite soumise aun ecoulement multi-etapes sous un gradient hydraulique qui augmente. L'apparition de l'instabiliteinterne est decrite de facon qualitative, a partir d'observations visuelles a travers la paroi du permeametre durant l'essai, ainsi que par des observations post-essai. L'instabiliteinterne est aussi decrite quantitativement apartir des variations du gradient hydraulique al'interieur des echantillons et du deplacement axial durant l'essai. Les resultats offrent une vision nouvelle de la progression spatiale et temporelle de l'instabiliteinterne causee par l'infiltration. Ces resultats apportent une meil-
173 citations
TL;DR: In this paper, the stability of a square tunnel in cohesive-frictional soils subjected to surcharge loading is studied. But the authors focus mainly on the stability and stability of the tunnel.
Abstract: This paper focuses mainly on the stability of a square tunnel in cohesive–frictional soils subjected to surcharge loading. Large-size noncircular tunnels are quickly becoming a widespread building ...
160 citations
TL;DR: In this article, the performance of a 26 m deep metro station excavation constructed by the top-down method in downtown Shanghai was extensively examined via a long-term comprehensive instrumentation program.
Abstract: Via a long-term comprehensive instrumentation program, the performance of a 26 m deep metro station excavation constructed by the top-down method in downtown Shanghai was extensively examined. The ...
144 citations
TL;DR: In this article, the system failure probability of a slope is different from the probability of failure along a slip surface, as sliding along any slip surface can cause slope failure, and the failure probability for a slope may have many possible slip surfaces.
Abstract: A slope may have many possible slip surfaces. As sliding along any slip surface can cause slope failure, the system failure probability of a slope is different from the probability of failure along...
139 citations
TL;DR: In this paper, the concept of progressive failure was used to explain translational progressive landslides and spreads, where the strain-softening behavior of the soil causes unstable forces to propagate a failure surface further in the slope.
Abstract: Observations from past events are used to show that the concept of progressive failure may explain translational progressive landslides and spreads — large landslides occurring in sensitive clays. During progressive failure, the strain-softening behaviour of the soil causes unstable forces to propagate a failure surface further in the slope. Translational progressive landslides generally take place in long, gently inclined slopes. Instability in a steeper upslope area is followed by redistribution of stress, which increases earth pressure further downslope. Passive failure may therefore occur in less-inclined ground, heaving the soil. Spreads are usually trigged by erosion of a deposit having a higher angle near the toe. Instability starts near the toe of the slope and propagates into the deposit, reducing earth pressure. This may lead to the formation of an active failure with dislocation of the deposit into horsts and grabens. The failure mechanism of both types of landslides is controlled by the stress...
132 citations
TL;DR: In this article, an alternative method to couple the hydraulic component with the mechanical component in a constitutive model for unsaturated soils is presented, which is based on hydromechanical coup...
Abstract: This paper presents an alternative method to couple the hydraulic component with the mechanical component in a constitutive model for unsaturated soils. Some pioneering work on hydromechanical coup...
127 citations
TL;DR: Differential subsidence of as much as 0.85m is affecting the access road to Umiujaq Airport in Nunavik (Quebec), Canada, located in the discontinuous permafrost zone as discussed by the authors.
Abstract: Differential subsidence of as much as 0.85 m is affecting the access road to Umiujaq Airport in Nunavik (Quebec), Canada, located in the discontinuous permafrost zone. A geotechnical and geophysica...
117 citations
TL;DR: In this paper, the authors examined the possibility of using the SWCC for the estimation of in situ soil suction and proposed a framework for estimating the median value for in situ suction along with a likely range of soil suctions values (i.e., maximum and minimum values).
Abstract: Soil-water characteristic curves (SWCCs) are routinely used for the estimation of unsaturated soil property func- tions (e.g., permeability functions, water storage functions, shear strength functions, and thermal property functions). This paper examines the possibility of using the SWCC for the estimation of in situ soil suction. The paper focuses on the limi- tations of estimating soil suctions from the SWCC and also suggests a context under which soil suction estimations should be used. The potential range of estimated suction values is known to be large because of hysteresis between drying and wetting SWCCs. For this, and other reasons, the estimation of in situ suctions from the SWCC has been discouraged. However, a framework is suggested in this paper for estimating the median value for in situ soil suction along with a likely range of soil suction values (i.e., maximum and minimum values). The percentage error in the estimation of soil suction from the SWCC is shown to be lowest for sand soils and highest for clay soils.
117 citations
TL;DR: The results of an experimental program undertaken to evaluate the impact of pore fluid salinity on the hydromechanical performance of light and dense backfill materials are presented in this article.
Abstract: The results of an experimental program undertaken to evaluate the impact of pore fluid salinity on the hydromechanical performance of light and dense backfill materials are presented Light and den
TL;DR: In this article, a hydromechanical path in stress (s 0 )-gradient (ijk) space is proposed, which describes the response to seepage flow during testing and terminates at the value of critical hydraulic gradient.
Abstract: Results are presented from permeameter tests involving unidirectional seepage flow through reconstituted speci- mens of four widely graded cohesionless soils. The onset of instability is defined by a significant decrease in local hy- draulic gradient over a relatively short period of time. The novel concept of a hydromechanical path in stress (s 0 )- gradient (ijk) space is proposed, which describes the response to seepage flow during testing and terminates at the value of critical hydraulic gradient. The path terminus establishes a hydromechanical boundary governing the onset of seepage- induced internal instability in one-dimensional flow. The boundary represents a failure envelope, which is different for each of the four soils tested. A ranking of seepage-induced instability for each soil, from most unstable to least unstable, is found similar, but not identical to, the susceptibility to internal instability determined from empirical analysis of the gra- dation shape. Resume´ : Des resultats d'essais en permeametre impliquant un ecoulement unidirectionnel a travers des echantillons re- constitues de quatre sols sans cohesion agranulometrie etalee sont presentes. Le debut de l'instabiliteest defini par une di- minution significative du gradient hydraulique local sur une periode de temps relativement courte. Le nouveau concept d'un cheminement hydromecanique dans l'espace contrainte (s 0) - gradient (ijk) est propose ´, qui decrit le comportement en ecoulement durant l'essai et qui se termine ala valeur du gradient hydraulique critique. Le point final du cheminement etablit une frontiere hydromecanique qui gere le debut de l'instabiliteinterne causee par l'infiltration en ecoulement uni- dimensionnel. La frontiere represente une enveloppe de rupture, qui est differente pour chacun des quatre sols testes. Un classement de l'instabilitecausee par l'infiltration pour chaque sol, du plus instable au moins instable, est semblable mais pas identique a la susceptibilitea l'instabiliteinterne determineeapartir d'analyses empiriques de la forme de la grada- tion. Mots-cles: infiltration, gradient hydraulique, contrainte effective, instabiliteinterne. (Traduit par la Redaction)
TL;DR: In this article, the authors show that tunneling in seismically active areas is vulnerable to adverse effects of earthquake loading and that there is a need to validate current design methods to better under...
Abstract: Tunnels in seismically active areas are vulnerable to adverse effects of earthquake loading. Recent seismic events have shown that there is a need to validate current design methods to better under...
TL;DR: In this article, the effects of tunneling-induced ground movement on pipelines, with special attention to the different soil responses to uplift and downward pipe-soil relative movements, are investigated.
Abstract: The underground space in urban areas is frequently congested with utilities, including pipelines and conduits, that are affected by underground construction, e.g., tunneling. This paper carries out finite element (FE) analyses to investigate the effects of tunneling-induced ground movement on pipelines, with special attention to the different soil responses to uplift and downward pipe–soil relative movements. A series of numerical parametric studies with 900 FE simulation runs in total is performed to encompass various combinations of ground settlement profiles, pipe dimensions, material properties, pipe burial depth, and soil properties that are typical for utility pipelines and tunnel construction in urban areas. The results are summarized in a dimensionless plot of relative pipe–soil stiffness versus ratio of maximum pipe curvature to maximum ground curvature, which can be used to directly estimate the maximum pipe bending strain and (or) to directly assess the tunneling-induced risk to pipelines. The ...
TL;DR: In this article, the undrained stability of a plane strain circular tunnel in clay is investigated, where the shear strength profile is assumed to increase linearly with depth and stability solutions for a var...
Abstract: This paper investigates the undrained stability of a plane strain circular tunnel in clay, where the shear strength profile is assumed to increase linearly with depth. Stability solutions for a var...
TL;DR: In this paper, the authors describe a new testing method to examine the mechanical behavior of railroad ballast subjected to repeated train passages on ballasted track and two types of cyclic loading tests.
Abstract: This paper describes a new testing method to examine the mechanical behavior of railroad ballast subjected to repeated train passages on ballasted track. Two types of cyclic loading tests, namely a...
TL;DR: To meet the increasing demand for underground space for economical development and infrastructural needs, more and more deep excavations have been constructed in Shanghai as discussed by the authors. But these excavations are not suitable for large-scale applications.
Abstract: To meet the increasing demand for underground space for economical development and infrastructural needs, more and more deep excavations have been constructed in Shanghai. In this paper, field perf...
TL;DR: In this article, the authors investigated the fine content influence on liquefaction potential of a single base sand mixed with three essentially nonplastic silts through strain-controlled monotonic undra...
Abstract: This study investigates the fines content influence on liquefaction potential of a single base sand mixed with three different essentially nonplastic silts through strain-controlled monotonic undra...
TL;DR: A number of potential offshore wind turbines in China will be constructed in sandy silt seabeds, and the mono-caisson foundation is an important choice for these offshore wind turbine as mentioned in this paper.
Abstract: A number of potential offshore wind turbines in China will be constructed in sandy silt seabeds, and the mono-caisson foundation is an important choice for these offshore wind turbines. A program o...
TL;DR: In this article, the physical condition of railway ballast should be regularly inspected and accordingly, ballast cleaning should be carried out to maintain the safe operation of a track, and a review of the current state of the art is presented.
Abstract: The physical condition of railway ballast should be regularly inspected and accordingly, ballast cleaning should be carried out to maintain the safe operation of a track. This paper reviews current...
TL;DR: In this article, a new model is proposed for the development of large landslides in sensitive clay, and supported by concepts from fracture mechanics, where the complete failure surface develops before the onset of significant movement, thus predetermining the final extent of failure.
Abstract: A new model is proposed for the development of large landslides in sensitive clay, and supported by concepts from fracture mechanics. A key assumption in this new model is that the complete failure surface develops before the onset of significant movement, thus predetermining the final extent of failure. The appearance of retrogression is actually the rear- ward advancing disruption of a monolithic slide mass over a growing zone of liquefied clay. It is seen that the likelihood of propagation of failure, and the resulting occurrence of a large landslide, depend primarily on the brittleness of the sensitive clay. The potential length of shear band propagation is limited by slope geometry, and increases for higher riverbanks and for flatter slopes above the riverbank. The model explains why large landslides in sensitive clay often terminate just adjacent to a reverse break in slope, such as an older landslide crater or a stream gully. The model also indicates that large landslides in sensitive clay could be expected to occur suddenly after a large single perturbation, such as an earthquake, or after a seemingly innocuous small trigger following the accumulation of a large number of annual load cycles, as observed fre- quently in nature.
TL;DR: In this article, the mechanism of instability in granular soils is explained, and its requirement as a forerunner to the liquefaction of level or sloping ground is described.
Abstract: The mechanism of instability in granular soils is explained and its requirement as a forerunner to the liquefaction of level or sloping ground is described. Case histories support the observation t...
TL;DR: In this article, the authors present test data that relate to the problem of tunneling beneath driven or jacked end-bearing piles in sand, where the model consisted of a tunnel and two piles a...
Abstract: This paper presents centrifuge model test data that relate to the problem of tunneling beneath driven or jacked end-bearing piles in sand. The centrifuge model consisted of a tunnel and two piles a...
TL;DR: In this paper, an experimental study of the effect of static shear stress on the undrained simple shear response of sands is presented, and the results show that simple shears are generally contractive.
Abstract: An experimental study of the effect of (initial) static shear stress on the undrained simple shear response of sands is presented. Liquefaction resistance of two sands, one generally contractive an...
TL;DR: In this paper, the dynamic response of tailings from a gold mine located in western Quebec was evaluated using cyclic laboratory testing and the tailings were classified as nonplastic silt and sand.
Abstract: The dynamic response of tailings from a gold mine located in western Quebec was evaluated using cyclic laboratory testing. These tailings are classified as nonplastic silt and sand. Specimens of th...
TL;DR: In this paper, the bearing capacity and settlement of foundations are determined experimentally or modelled numerically based on conventional soil mechanics for saturated soils for both saturated and non-saturated soils.
Abstract: The bearing capacity and settlement of foundations are determined experimentally or modelled numerically based on conventional soil mechanics for saturated soils. In both methods, bearing capacity ...
TL;DR: In this article, a joint industry project, undertaken by the Norwegian Geotechnical Institute and the Centre for Offshore Foundation Systems at The Univer- sity of Western Australia, on the use of in situ testing for the characterization of deepwater soft soils is presented.
Abstract: Offshore developments for hydrocarbon resources have now progressed to water depths approaching 3000 m, with geotechnical design increasingly focused on soft sediments in the upper 30 m or so of the seabed. Due to the difficul- ties and high cost in recovering high-quality samples from deepwater sites, there is increasing dependence on in situ testing techniques for determining the geotechnical design parameters. This paper summarizes the findings from a joint industry project, undertaken by the Norwegian Geotechnical Institute and the Centre for Offshore Foundation Systems at The Univer- sity of Western Australia, on the use of in situ testing for the characterization of deepwater soft soils. The project focused on theoretical and empirical studies for the interpretation of piezocone, T-bar, and ball penetration test data, linking the pen- etration resistance to shear strengths determined from in situ vane tests and laboratory tests on high-quality samples. Guide- lines are summarized for interpreting in situ test data, particularly for estimating intact and remoulded undrained shear strengths from the penetration resistance measured by each type of penetrometer. Suggestions are also given for future de- velopment of in situ testing techniques to maximize the potential of in situ testing in characterization of deepwater soft soils.
TL;DR: In this paper, a 3D finite element (FE) model is developed to simulate the pullout behavior of a soil nail in a soil-nail pullout box under different overburden and grouting conditions.
Abstract: In this paper, a three-dimensional (3D) finite element (FE) model is developed to simulate the pullout behaviour of a soil nail in a soil-nail pullout box under different overburden and grouting pr...
TL;DR: In natural and engineered soils, water infiltration into a cracked soil often starts from unsaturated conditions, the soil-water characteristic curve (SWCC) and permeab... as discussed by the authors.
Abstract: Cracks are widely present in natural and engineered soils. As water infiltration into a cracked soil often starts from unsaturated conditions, the soil-water characteristic curve (SWCC) and permeab...
TL;DR: In this article, the interparticle friction between sand-sized grains over relatively large displacements and also under immersion in a fluid was measured using simple spherical particle contacts and the forces at those contacts revealed that there are strict constraints on the permissible stiffness of the interbody friction apparatus to avoid stick-slip behaviour.
Abstract: A new apparatus is described that measures interparticle friction between sand-sized grains over relatively large displacements and also under immersion in a fluid. Its relatively simple design allows the key calibrations to be checked by statics. An analysis of the geometry of simple spherical particle contacts and the forces at those contacts revealed that there are strict constraints on the permissible stiffness of the interparticle friction apparatus to avoid stick-slip behaviour. Tests on ball bearings gave highly repeatable data, while others on glass ballotini revealed a significant effect of ambient humidity on the data obtained. The interparticle friction was found to increase with the roughness of the ballotini. Immersion in water increased the interparticle friction slightly for both the ballotini and quartz sand particles, while immersion in oil reduced the friction considerably for the quartz sand, especially at higher contact force levels.