Microstructure evolution of granular soils in cyclic mobility and post-liquefaction process

Wang, Gang; Wei, Jiangtao

doi:10.1007/s10035-016-0621-5

Cited by 98 publications

(33 citation statements)

References 29 publications

(35 reference statements)

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“…14,15,17,28,[30][31][32][33] Li and Yu 15 performed two-dimensional DEM simulations of PSR with polygon samples enclosed by rigid walls. Periodic boundaries 26,[34][35][36] are widely used to reduce the boundary effects induced by rigid walls. Different types of flexible boundaries have also been proposed.…”

Section: Direct Application Of Stress Boundary Conditionsmentioning

confidence: 99%

3D DEM simulation of principal stress rotation in different planes of cross‐anisotropic granular materials

Xue

Kruyt

Wang

et al. 2019

Num Anal Meth Geomechanics

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Summary Three‐dimensional Discrete Element Method simulations have been performed to study the deformation of cross‐anisotropic granular materials under principal stress rotation (PSR), for rotation planes oriented at different angles θ with respect to the bedding plane. The simulations have been conducted with a novel technique for applying specified stresses at three‐dimensional boundaries. The results are qualitatively in agreement with experimental results from literature. Cumulative volume contraction is always observed under continuous PSR and increases with increasing θ. The dilatancy rate decreases with increasing number of PSR cycles, tending to zero. The noncoaxiality angle between the strain increment and the stress in the PSR plane increases with increasing number of cycles, reaching the same asymptotic value for samples of various densities and for various θ. Periodic oscillations of the dilatancy rate and noncoaxiality angle within each PSR cycle are observed with an increasing oscillation magnitude with increasing θ, due to the larger fabric anisotropy within the PSR plane. When θ = 30 or 60°, significant noncoaxial strain accumulation occurs in the plane perpendicular to the PSR plane due to the oblique angle between the PSR plane and the bedding plane, echoing the major principal fabric direction's being neither parallel nor perpendicular to the PSR plane. The macroscopic behavior of the samples is related to the microscopic parameters including coordination number and fabric anisotropy. With increasing number of cycles, the difference between normalized stress/strain/fabric increment tensors tends to become constant, with only a small lag between each pair, irrespective of θ.

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Section: Direct Application Of Stress Boundary Conditionsmentioning

confidence: 99%

3D DEM simulation of principal stress rotation in different planes of cross‐anisotropic granular materials

Xue

Kruyt

Wang

et al. 2019

Num Anal Meth Geomechanics

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“…Xu et al [17] carried out a series of 3D constant-volume cyclic triaxial tests to link the liquefaction resistance to shear wave velocity. Wang and Wei [18] quantified the particle-void arrangement of granular soils in cyclic mobility and post-liquefaction stages based on 2D DEM simulations. Wang et al [19] proposed a new micro-scale parameter, mean neighbouring particle distance (MNPD), to describe the development of shear strain post liquefaction.…”

Section: Introductionmentioning

confidence: 99%

DEM analysis of the onset of flow deformation of sands: linking monotonic and cyclic undrained behaviours

et al. 2018

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Z 2018, 'DEM analysis of the onset of flow deformation of sands: linking monotonic and cyclic undrained behaviours', Acta geotechnica. https://doi. AbstractThis study explores the link between the monotonic and cyclic undrained behaviour of sands using the discrete element method (DEM). It is shown that DEM can effectively capture the flow deformation of sands sheared under both monotonic and cyclic undrained loading conditions. When subjected to cyclic shearing, flow-type failure is observed for a loose sample, while cyclic mobility is observed for a dense sample. A strong correlation between the monotonic and cyclic loading behaviour that has been revealed experimentally is also confirmed in DEM simulations: a) flow deformation occurs in the compressive loading direction when the cyclic stress path intersects the monotonic compression stress path prior to the monotonic extension stress path, and vice versa; b) the onset of flow deformation in q-p' space is located in the zone bounded by the critical state line and the instability line determined from monotonic simulations. Hill's condition of instability is shown to be effective to describe the onset of flow failure. Micro-mechanical analyses reveal that flow deformation is initiated when the index of redundancy excluding floating particles drops to below 1.0 under both monotonic and cyclic loading conditions. Flow deformation induced by either monotonic or cyclic loading is characterized by abrupt change of structural fabric which is highly anisotropic. The reason why the dense sample * Corresponding author: Email: xhuang@tongji.edu.cn; Phone: +86 (0)21 6598 4551; Fax: +86 (0)21 6598 4551 2 dilated during monotonic loading but showed cyclic mobility (temporary liquefaction) during cyclic loading is attributed to the repeating reversal of loading direction, which leads to the periodic change of microstructure.

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“…The DGML has the broad capability to search for ground-motion time histories in the library database on the basis of response spectral shape, characteristics of the recordings in terms of earthquake magnitude and type of faulting distance, site characteristics, duration, and presence of velocity pulses in nearfault time histories. These ground-motion intensity measures have been found to be important in liquefaction and seismic assessment of a variety of geotechnical systems (Du and Wang, 2014;Wang, 2015a, b, 2017;Wang and Wei, 2016;Wang, 2015, 2016;Zhang and Wang, 2016). The DGML Search Engine window is shown in Fig.…”

Section: The Nga Database and Dgmlmentioning

confidence: 99%

A procedure to select ground-motion time histories for deterministic seismic hazard analysis from the Next Generation Attenuation (NGA) database

Huang

Zhu

2017

Nat. Hazards Earth Syst. Sci.

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Abstract. In performance-based seismic design, groundmotion time histories are needed for analyzing dynamic responses of nonlinear structural systems. However, the number of ground-motion data at design level is often limited. In order to analyze seismic performance of structures, ground-motion time histories need to be either selected from recorded strong-motion database or numerically simulated using stochastic approaches. In this paper, a detailed procedure to select proper acceleration time histories from the Next Generation Attenuation (NGA) database for several cities in Taiwan is presented. Target response spectra are initially determined based on a local ground-motion prediction equation under representative deterministic seismic hazard analyses. Then several suites of ground motions are selected for these cities using the Design Ground Motion Library (DGML), a recently proposed interactive ground-motion selection tool. The selected time histories are representatives of the regional seismic hazard and should be beneficial to earthquake studies when comprehensive seismic hazard assessments and site investigations are unavailable. Note that this method is also applicable to site-specific motion selections with the target spectra near the ground surface considering the site effect.

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Microstructure evolution of granular soils in cyclic mobility and post-liquefaction process

Cited by 98 publications

References 29 publications

3D DEM simulation of principal stress rotation in different planes of cross‐anisotropic granular materials

3D DEM simulation of principal stress rotation in different planes of cross‐anisotropic granular materials

DEM analysis of the onset of flow deformation of sands: linking monotonic and cyclic undrained behaviours

A procedure to select ground-motion time histories for deterministic seismic hazard analysis from the Next Generation Attenuation (NGA) database

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