Fabric characteristics and processes influencing the liquefaction and re-liquefaction of sand.

Wang, Rui; Fu, Pengcheng; Zhang, Jianmin; Dafalias, Yannis F.

doi:10.1016/j.soildyn.2019.105720

Cited by 72 publications

(22 citation statements)

References 43 publications

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“…In addition, some research reported that the cone penetration resistance and shear wave velocity ( V s ) are influence by sand fabrics 58,59 . The initial anisotropy degree can be quantified by the in situ CPT or V s tests. The maximum double amplitude axial strain of the initial liquefaction states indeed affected reliquefaction resistance of completely consolidated samples, which was reported by Wang et al 60 . and Morimoto et al 26 .…”

Section: Discussionsupporting

confidence: 54%

“…3. The maximum double amplitude axial strain of the initial liquefaction states indeed affected reliquefaction resistance of completely consolidated samples, which was reported by Wang et al 60 and Morimoto et al 26 The double amplitude axial strain may also affect reliquefaction resistance of incompletely consolidated samples. However, this study aimed to explore the effects of aftershock intensity and the consolidation degree without concern on the previous double amplitude axial strain.…”

Section: Discussionmentioning

confidence: 55%

“…Previous reliquefaction research focused on reliquefaction behaviors of reconsolidated soil without residual EPWP, including element tests, [15][16][17] shaking table model tests, [18][19][20][21][22][23][24] cyclic biaxial tests, 25 and DEM simulations. [26][27][28] However, the sand deposits may be shaken by the aftershocks when the ever-liquefied deposits are not completely reconsolidated as discussed before. The effect of U r on reliquefaction resistance and its related mesoscopic mechanism remain unknown, which inspired this study.…”

Section: Introductionmentioning

confidence: 99%

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Effects of reconsolidation degree on reliquefaction resistance under mainshock–aftershock sequences: A DEM investigation

Xie

Zhao

2022

Num Anal Meth Geomechanics

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Aftershock events may immediately follow mainshock events. In liquefiable deposits, the excess pore pressure caused by mainshock events may not dissipate completely in a short time interval between the mainshock and the aftershock. Sandy soil with different reconsolidation degrees (Ur) may present different reliquefaction resistances during the aftershock, which was not fully considered into the previous studies of reliquefaction. In this study, discrete element method (DEM) was employed to simulate a series of cyclic triaxial tests to evaluate the effects of Ur on reliquefaction resistance under mainshock–aftershock seismic sequence. The initially liquefied specimen was reconsolidated from two states with small and large residual shear strain respectively. Reconsolidated specimens reliquefied under different cyclic stress ratios (CSRs). Simulation results show that reliquefaction resistance increased gradually with increasing Ur, which was closely related to the previous residual shear strain during the first liquefaction event. Specimens that having large residual shear strain reliquefied easily, and the reliquefaction resistance of those specimens increased slightly with increasing Ur. On the contrary, reliquefaction resistance of the specimens that having small residual shear stain increased obviously with increasing Ur. The ratio of initial mechanical average coordination number to initial mesoscopic fabric anisotropy of reconsolidated specimens had a good correlation to the contraction potential and increased gradually with increasing Ur.

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Section: Discussionsupporting

confidence: 54%

Section: Discussionmentioning

confidence: 55%

Section: Introductionmentioning

confidence: 99%

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Effects of reconsolidation degree on reliquefaction resistance under mainshock–aftershock sequences: A DEM investigation

Xie

Zhao

2022

Num Anal Meth Geomechanics

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“…DEM numerical tests on virtual granular materials offer a convenient alternative. Though DEM test results may differ quantitatively from their physical world counterparts, studies have shown that the qualitative behavior patterns of sand can be reproduced for monotonic loading, 27,29,30 cyclic loading, 85,86 and PSAR 7,8,40,66 . Xue et al 8 proposed a 3D force‐line method to apply arbitrary stress boundary conditions on DEM specimens that allows for the application of any 3D stress paths, which enables simulations with principal stress axes rotating in any arbitrary plane as is in engineering reality.…”

Section: Model Performance For Dem Numerical Tests Under 3d Psarmentioning

confidence: 99%

Three‐dimensional anisotropic plasticity model for sand subjected to principal stress value change and axes rotation

Xue

Pan

et al. 2020

Num Anal Meth Geomechanics

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A three‐dimensional (3D) anisotropic plasticity model for sand is formulated in this study to provide a constitutive description for both radial and principal stress axes rotation (PSAR) loading‐induced behavior under various conditions with a single set of model parameters. The model has zero elastic range, with plastic loading and flow direction dependent on both current stress and stress rate direction. Fabric tensor is introduced along with its evolution to achieve anisotropic plastic modulus, dilatancy, and flow rule formulations. Increase in plastic modulus under continuous PSAR achieves eventual convergence of strain accumulation. A unique decomposition of dilatancy controls the overall contraction and periodic dilatancy oscillation under PSAR. The performance of the model is first thoroughly evaluated based on drained/undrained, monotonic shear/PSAR tests on Toyoura sand, showing its effectiveness in reproducing the behavior of real sand. Discrete element method numerical test results are then adopted for comprehensive calibration of the model parameters, and then for validation of the model under 3D PSAR in any arbitrary direction. These comparisons highlight the model's capability in simulating the behavior of granular soil under 3D stress paths.

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“…Wang and Wei [68] and Wang et al [69] came up with the centroid distance and mean neighboring particle distance, respectively, to explore the potential microscopic indicators influencing the post-liquefaction large deformation. Other topics of special interest for undrained cyclic shearing include, but are not limited to, fabric anisotropy evolution [53,60,72] and effects of initial and loading conditions on liquefaction resistance [16,41,70,74,80], to name a few. Recently, Wei [71] and Wei et al [73] conducted DEM simulations of a granular packing subjected to uni-and multidirectional cyclic shearing.…”

Section: Introductionmentioning

confidence: 99%

Evolution of granular media under constant-volume multidirectional cyclic shearing

et al. 2021

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By means of the three-dimensional discrete element method, we study the long-time evolution toward liquefaction state in granular materials composed of spherical particles under multidirectional cyclic shearing at constant volume. Extensive simulations were carried out along 1-D linear, 2-D linear, circular/oval, and 8-like shear paths, and the evolution of the system was analyzed in terms of pore pressure, shear strain, and granular texture. The macroscopic stress path and stressstrain response agree well with laboratory experiments. We find that the liquefaction resistance, i.e., the number of cycles necessary to reach the liquefaction state, is generally lower under multidirectional loading as compared to unidirectional loading. As the transient vanishing of mean stress does not occur for all stress paths, we introduce a shear strain-based liquefaction criterion that can be consistently applied to all strain paths. The granular texture is monitored through the coordination number, particle connectivity, force and fabric anisotropies, and friction mobilization. In particular, a particlevoid descriptor, named centroid distance, is found to be closely related to the shear strain accumulation. We show that the force anisotropy tensors become almost proportional to the deviatoric stress tensor more quickly than the fabric anisotropy tensor, which takes most of the pre-liquefaction period to follow the external loading. The relationship between deviatoric stress ratio and the force and fabric anisotropies, known to hold in monotonic triaxial loading, also holds with high accuracy in the studied multidirectional cyclic shearing paths; the contributing weights of the anisotropies level off in the post-liquefaction period and do not depend on the shear path.

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Fabric characteristics and processes influencing the liquefaction and re-liquefaction of sand.

Cited by 72 publications

References 43 publications

Effects of reconsolidation degree on reliquefaction resistance under mainshock–aftershock sequences: A DEM investigation

Effects of reconsolidation degree on reliquefaction resistance under mainshock–aftershock sequences: A DEM investigation

Three‐dimensional anisotropic plasticity model for sand subjected to principal stress value change and axes rotation

Evolution of granular media under constant-volume multidirectional cyclic shearing

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