Strength Loss and Localization at Silt Interlayers in Slopes of Liquefied Sand

Kulasingam, R.; Malvick, Erik J.; Boulanger, Ross W.; Kutter, Bruce L.

doi:10.1061/(asce)1090-0241(2004)130:11(1192)

Cited by 83 publications

(19 citation statements)

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“…(a) Experiments on a granular avalanche in a convex and concave curve chute [7] or on granular flows down a rough inclined plane [8]; physical model tests such as centrifuge tests on soil slopes under different conditions, such as rainfalls [9,10] or shaking [11]; (b) Numerical analyses mainly by the finite element method [12][13][14] or by the distinct element method.…”

Section: Introductionmentioning

confidence: 99%

“…They found that different acceleration direction leads to different type of slope failure and heterogeneity may be a major control on the size distribution of natural landslide inventories. Malvick et al [18,19] proposed a new method for estimating the susceptibility of a layered, liquefiable, infinite slope to shear deformations associated with void redistribution, in which shear localizations, and water films have been observed in delayed slope failures at interfaces between liquefied sand and lower permeability soil [11,20]. The loss of shear strength in slopes is potentially affected by void redistribution, whereas a part of the liquefied soil can locally loosen whereas another part densifies [21].…”

Section: Introductionmentioning

confidence: 99%

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Distinct element method analyses of idealized bonded-granulate cut slope

Jiang

Murakami

2012

Granular Matter

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This paper presents a numerical study of idealized bonded-granulate cut slope subject to sudden strength reduction. A 2-D Distinct Element Method (DEM) has been used to carry out a simulation of full-process slope failure with focus on very-rapid and extremely-rapid landslide process. The numerical results show that during the landslide process: (1) the soil moves either in a rather random/chaotic way (diffuse failure) or in different curved shear bands (localized failure). The soil close to slope surface moves along downward slope while the soil close to the slope toe moves significantly in the horizontal direction. The landslide experiences very rapid flow most of the time, with its maximum velocity increaseing obviously with time at first to its peak value, then decreasing gradually to zero. (2) The soil close to slope undergo a repeated loading and unloading process, and an evident rotation of principal stresses. Their stress state may arrive slightly over the peak strength envelope as a result of extremely rapid flow. (3) There is little grain-size effect for the grains at low velocity, but an evident grain-size effect for the grains at high velocity, with large-size grains tending to move fast. (4) The post-failure inclination is much smaller than the peak/residual internal friction angle of the material.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Distinct element method analyses of idealized bonded-granulate cut slope

Jiang

Murakami

2012

Granular Matter

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“…It has been recognized that certain failures that occurred following earthquakes (e.g., the Lower San Fernando Dam, the Mochikoshi Tailings Dam) were due to void redistribution caused by excess pore-pressure equalization (Idriss 2004;Okusa et al 1984). Changes in soil permeability that occur because of natural layering may also significantly influence the behaviour of a soil deposit by impeding water flow (Kokusho 1999;Kulasingam et al 2004). Such boundary constraints might be expected to induce conditions more damaging than the undrained state.…”

Section: Introductionmentioning

confidence: 99%

Behaviour of sands under generalized drainage boundary conditions

Sivathayalan¹,

Logeswaran²

2007

Can. Geotech. J.

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An experimental study of the behaviour of sands under generalized drainage boundary conditions is presented. The influence of partially drained conditions, which generally is a reflection of the loading rate and the permeability of the soil, has been studied by limiting the volumetric deformation between drained and undrained states. The effect of potential pore-pressure variations in situ has been assessed by simulating various levels of volumetric deformation during shear. Conventional drained and undrained tests were also carried out on the same sands to enable a direct evaluation of the effect of drainage. A triaxial device with the ability to control strain-paths was used to carry out the tests, and all tests were performed under compression loading with no change in total lateral stress. A systematic change in the stress-strain response was noted as the drainage conditions gradually change from drained to undrained. The maximum excess pore pressure generated owing to inhibition of drainage is almost linearly related to the amount of drainage blocked. These results support the contention that the undrained state may not represent the most damaging scenario under field loading conditions. Much smaller minimum shear strength values compared with the undrained strength were measured when pore-pressure boundary conditions caused expansive volume changes. The domain of strain-softening response, and hence liquefaction susceptibility, increased owing to such loading. Résumé :On présente une étude expérimentale du comportement des sables dans des conditions généralisées de drainage aux frontières. On a étudié l'influence des conditions partiellement drainées, qui s'explique généralement par la vitesse de chargement et la perméabilité du sol, en limitant la déformation volumétrique entre les états drainés et non drainés. L'effet des variations potentielles de la pression interstitielle in situ a été évalué en simulant divers niveaux de déformation volumétrique au cours du cisaillement. On a aussi fait des essais traditionnels drainés et non drainés sur les mêmes sables pour permettre une évaluation directe de l'effet du drainage. Un appareil triaxial à cheminement de contrainte contrôlé a été utilisé lors des essais, et tous les essais ont été effectués sous un effort de compression sans changement aux contraintes latérales totales. On a observé un changement systématique de la réponse contraintedéformation lorsque les conditions de drainage changeaient graduellement de drainées à non drainées. L'excédent maximum de pression interstitielle généré dû à l'inhibition du drainage est presque en relation linéaire avec la quantité de drainage bloqué. Ces résultats appuient la contention que l'état non drainé peut ne pas représenter le scénario le plus dommageable dans les conditions de chargement sur le terrain. On a mesuré des valeurs minimales de résistance au cisaillement beaucoup plus petites que celles de la résistance non drainée lorsque les conditions de pression interstitielle aux frontières produisaient des chang...

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“…Small strains were observed in the dense sand layer, and shear strains in the loose sand were largest near the interface between the loose sand and clay. Most of the ground surface displacement was attributed to a displacement discontinuity at the interface between the sand and clay that formed when void redistribution weakened a zone in the loose sand immediately beneath the clay ͑e.g., Kulasingam et al 2004͒. Predicting the discontinuous distribution of soil displacements is quite difficult, so the response of a pile group to a continuous soil displacement profile is explored later.…”

Section: Ground-displacementsmentioning

confidence: 99%

Static Pushover Analyses of Pile Groups in Liquefied and Laterally Spreading Ground in Centrifuge Tests

Brandenberg

Boulanger

Kutter

et al. 2007

J. Geotech. Geoenviron. Eng.

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Monotonic, static beam on nonlinear Winkler foundation ͑BNWF͒ methods are used to analyze a suite of dynamic centrifuge model tests involving pile group foundations embedded in a mildly sloping soil profile that develops liquefaction-induced lateral spreading during earthquake shaking. A single set of recommended design guidelines was used for a baseline set of analyses. When lateral spreading demands were modeled by imposing free-field soil displacements to the free ends of the soil springs ͑BNWF_SD͒, bending moments were predicted within −8% to +69 ͑16th to 84th percentile values͒ and pile cap displacements were predicted within −6 to +38%, with the accuracy being similar for small, medium, and large motions. When lateral spreading demands were modeled by imposing limit pressures directly to the pile nodes ͑BNWF_LP͒, bending moments and cap displacements were greatly overpredicted for small and medium motions where the lateral spreading displacements were not large enough to mobilize limit pressures, and pile cap displacements were greatly underpredicted for large motions. The effects of various parameter relations and alternative design guidelines on the accuracy of the BNWF analyses were evaluated. Sources of bias and dispersion in the BNWF predictions and the issues of greatest importance to foundation performance are discussed. The results of these comparisons indicate that certain guidelines and assumptions that are common in engineering design can produce significantly conservative or unconservative BNWF predictions, whereas the guidelines recommended herein can produce reasonably accurate predictions.

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Strength Loss and Localization at Silt Interlayers in Slopes of Liquefied Sand

Cited by 83 publications

References 20 publications

Distinct element method analyses of idealized bonded-granulate cut slope

Distinct element method analyses of idealized bonded-granulate cut slope

Behaviour of sands under generalized drainage boundary conditions

Static Pushover Analyses of Pile Groups in Liquefied and Laterally Spreading Ground in Centrifuge Tests

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