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Multiscale hydro-mechanical analysis of unsaturated granular materials using bridging scale method

Ke Wan (Department of Engineering Mechanics, Dalian University of Technology, Dalian, China and The State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu, China.)
Xikui Li (The State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian, China.)

Engineering Computations

ISSN: 0264-4401

Article publication date: 15 June 2015

335

Abstract

Purpose

The purpose of this paper is to extend the bridge scale method (BSM) developed for granular materials with only the solid phase to that taking into account the effects of wetting process in porous continuum. The granular material is modeled as partially saturated porous Cosserat continuum and discrete particle assembly in the coarse and fine scales, respectively.

Design/methodology/approach

Based on the mass and momentum conservation laws for the three phases, i.e. the solid skeleton, the pore water and the pore air, the governing equations for the unsaturated porous Biot-Cosserat continuum model in the coarse scale are derived. In light of the passive air pressure assumption, a reduced finite element model for the model is proposed. According to the decoupling of the fine and coarse scale calculations in the BSM, the unsaturated porous Cosserat continuum model using the finite element method and the discrete element model using the discrete element method for granular media are combined.

Findings

The numerical results for a 2D example problem of slope stability subjected to increasing rainfall along with mechanical loading demonstrate the applicability and performance of the present BSM. The microscopic mechanisms of macroscopic shear band developed in the slope are demonstrated.

Research limitations/implications

Do not account for yet the effects of unsaturated pore water in the fine scale.

Originality/value

The novel BSM that couples the Biot-Cosserat porous continuum modeling and the discrete particle assembly modeling in both coarse and fine scales, respectively, is proposed to provide a micro-macro discrete-continuum two-scale modeling approach for numerical simulations of the hydro-mechanical coupling problems in unsaturated granular materials.

Keywords

Acknowledgements

The authors are pleased to acknowledge the support of this work by the National Natural Science Foundation of China through contract/grant numbers 11372066, 11072046, 11402038 and the National Key Basic Research and Development Program (973 Program) through contract number 2010CB731502.

Citation

Wan, K. and Li, X. (2015), "Multiscale hydro-mechanical analysis of unsaturated granular materials using bridging scale method", Engineering Computations, Vol. 32 No. 4, pp. 935-955. https://doi.org/10.1108/EC-04-2014-0083

Publisher

:

Emerald Group Publishing Limited

Copyright © 2015, Emerald Group Publishing Limited

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