Strain Localization in Unsaturated Elastic-Plastic Materials Subjected to Plane Strain Compression

Perić, Dunja; Zhao, Gao‐Feng; Khalili, Nasser

doi:10.1061/(asce)em.1943-7889.0000767

Cited by 16 publications

(8 citation statements)

References 28 publications

(34 reference statements)

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“…Presented in Figure are the variations of the deviatoric stress, volumetric strain, and suction versus the axial strain for the constant water content analysis. In all cases, the ESPIM results are compared with the numerical results presented in Perić et al, which were already verified using a series of conventional triaxial compression tests performed on Bourke silt by Uchaipichat and Khalili . In all cases, perfect agreements are observed between the results of this study and the reference solutions in Perić et al…”

Section: Numerical Examplessupporting

confidence: 76%

“…The bounding surface plasticity model implemented in the ESPIM developed in this study is examined in this example, which concerns a series of PSC tests conducted on unsaturated Bourke silt from the Bourke region of New South Wales, Australia, as reported in Perić et al The elastoplastic behaviour of the material is captured using the bounding surface plasticity model presented in Section . The model parameters are selected the same as those presented in Perić et al, which are also listed in Table . Suction dependency of the LICL parameters ( λ and N ) is summarised in Table .…”

Section: Numerical Examplesmentioning

confidence: 99%

“…The tests involve application of a vertical compressive strain to the top of the medium at the constant rate of 10 −6 s −1 . In the numerical simulations, a stationary SWRC with no hydraulic hysteresis is considered in accordance with the assumptions in Perić et al 112 A constant time step of Δt = 1 s is assumed throughout the analyses. Two sets of drained simulations with initial net stresses of 30 and 100 kPa are carried out.…”

Section: Psc Problemmentioning

confidence: 99%

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Fully coupled elastoplastic hydro‐mechanical analysis of unsaturated porous media using a meshfree method

Ghaffaripour

Esgandani

Khoshghalb

et al. 2019

Num Anal Meth Geomechanics

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Summary This paper presents the first application of an advanced meshfree method, ie, the edge‐based smoothed point interpolation method (ESPIM), in simulation of the coupled hydro‐mechanical behaviour of unsaturated porous media. In the proposed technique, the problem domain is spatially discretised using a triangular background mesh, and the polynomial point interpolation method combined with a simple node selection scheme is adopted for creating nodal shape functions. Smoothing domains are formed on top of the background mesh, and a constant smoothed strain, created by applying the smoothing operation over the smoothing domains, is assigned to each smoothing domain. The deformation and flow models are developed based on the equilibrium equation of the mixture, and linear momentum and mass balance equations of the fluid phases, respectively. The effective stress approach is followed to account for the coupling between the flow and deformation models. Further coupling among the phases is captured through a hysteretic soil water retention model that evolves with changes in void ratio. An advanced elastoplastic constitutive model within the context of the bounding surface plasticity theory is employed for predicting the nonlinear behaviour of soil skeleton. Time discretisation is performed by adopting a three‐point discretisation method with growing time steps to avoid temporal instabilities. A modified Newton‐Raphson framework is designed for dealing with nonlinearities of the discretised system of equations. The performance of the numerical model is examined through a number of numerical examples. The state‐of‐the‐art computational scheme developed is useful for simulation of geotechnical engineering problems involving unsaturated soils.

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Section: Numerical Examplessupporting

confidence: 76%

Section: Numerical Examplesmentioning

confidence: 99%

Section: Psc Problemmentioning

confidence: 99%

See 1 more Smart Citation

Fully coupled elastoplastic hydro‐mechanical analysis of unsaturated porous media using a meshfree method

Ghaffaripour

Esgandani

Khoshghalb

et al. 2019

Num Anal Meth Geomechanics

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“…This is more intense inside the localized zone, where shearing results in further reduction in volume. Such contractant shear banding is a primary mode of localized deformation in normally consolidated and lightly over-consolidated unsaturated soils under compression by Peric et al 69 Figure 7 shows the deformed meshes at different strain levels. At low levels of overall axial strain (ranging from 0% to 5%), homogenous deformations are observed.…”

Section: Numerical Results Of Strain Localizationmentioning

confidence: 99%

A computational model for dynamic strain localization in unsaturated elasto‐viscoplastic soils

Oka

Shahbodagh

Kimoto

2018

Num Anal Meth Geomechanics

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Summary Strain localization has been the subject of extensive theoretical and numerical studies over the last four decades. The static and dynamic strain localization in both dry and water‐saturated geomaterials has widely been investigated numerically. However, studies on unsaturated geomaterials have been insufficient. This paper presents a computational model for nonlinear dynamic analysis of strain localization in multiphase geomaterials. The discretization of the governing equations is achieved using the finite element method in the finite deformation regime with the updated Lagrangian description. An elasto‐viscoplastic model extended to include the effect of suction on the behavior of partially saturated clay is used in the formulation. The nonlinear kinematic hardening rule and softening due to the structural degradation of soil particles are taken into account in the model. The inception and progression of localization in fully saturated and unsaturated clay under dynamic compressive loading are investigated. In the unsaturated case, the strain localization becomes more pronounced and much clearer shear bands are formed. More brittleness is observed in the unsaturated case due to the collapse of suction force caused by shearing. This demonstrates that even though suction improves the mechanical properties of soil, ie, increasing the stiffness and shear strength, the hypothesis of fully saturation is not at all on the side of safety due to the drastic loss of strength associated with the collapse of suction which may cause a strong strain localization.

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“…The numerical results demonstrated that the spatial variations of density and fluid saturation have a major influence on the inception of localized deformation in unsaturated soils. Researchers also investigated the bifurcation of unsaturated geomaterials at the material point level via constitutive modeling …”

Section: Introductionmentioning

confidence: 99%

Strain localization in a solid‐water‐air system with random heterogeneity via stabilized mixed finite elements

Song

Wang

2017

Numerical Meth Engineering

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Unsaturated soils are solid-water-air systems that include a solid skeleton, pore water, and pore air. Heterogeneities in porosity or degree of saturation are salient features of unsaturated soils. These heterogeneities may trigger localized deformation (eg, shear banding) in such materials as demonstrated by numerical simulations via a pseudo three-phase model. In this article, we formulate a true three-phase mathematical framework implemented via stabilized low-order mixed finite elements. With this mathematical framework, we study the evolution of pore air pressure and its role in the inception of strain localization triggered by initial heterogeneity either in porosity or suction. The numerical simulations show that pore air pressure is nonzero and nonuniform in the process of progressive failure in unsaturated soils.The heterogeneity of pore air pressure may also play a significant role in the onset of localized deformation of unsaturated soils. Therefore, a three-phase model considering the pore air phase is physically more appropriate for modeling strain localization in unsaturated soils.

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Strain Localization in Unsaturated Elastic-Plastic Materials Subjected to Plane Strain Compression

Cited by 16 publications

References 28 publications

Fully coupled elastoplastic hydro‐mechanical analysis of unsaturated porous media using a meshfree method

Fully coupled elastoplastic hydro‐mechanical analysis of unsaturated porous media using a meshfree method

A computational model for dynamic strain localization in unsaturated elasto‐viscoplastic soils

Strain localization in a solid‐water‐air system with random heterogeneity via stabilized mixed finite elements

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