Title: Strength anisotropy of granular material consisting of perfectly round particles

Abstract

Abstract The strength anisotropy of granular materials deposited under gravity has mostly been attributed to elongated particles' tendency to align long axes along the bedding plane direction. However, recent experiments on near‐spherical glass beads, for which preferred particle alignment is inapplicable, have exhibited surprisingly strong strength anisotropy. This study tests the hypothesis that certain amount of fabric anisotropy caused by the anisotropic stress during deposition under gravity can be locked in a circular‐particle deposit. Such locked‐in fabric anisotropy can withstand isotropic consolidation and leads to significant strength anisotropy. 2D discrete element method simulations of direct shear tests on circular‐particle deposits are conducted in this study, allowing for the monitoring of both stress and fabric. Simulations on both monodispersed and polydispersed circular‐particle samples generated under downward gravitational acceleration exhibit clear anisotropy in shear strength, thereby proving the hypothesis. When using contact normal‐based and void‐based fabric tensors to quantify fabric anisotropy in the material, we find that the intensity of anisotropy is discernible but low prior to shearing and is dependent on the consolidation process and the dispersity of the sample. The fact that samples with very low anisotropy intensity measurements still exhibit fairly strong strength anisotropy suggests that current typical contactmore » normal‐based and void‐based second‐order fabric tensor formulations may not be very effective in reflecting the anisotropic peak shear strength of granular materials. Copyright © 2017 John Wiley & Sons, Ltd.« less

Authors:

Wang, Rui  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-1607-9783"

Fu, Pengcheng  ^[2];

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• Search DOE PAGES for ORCID "0000-0002-7408-3350"

Tong, Zhaoxia ^[3]; Zhang, Jian‐Min ^[1]; Dafalias, Yannis F. ^[4]

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+ Show Author Affiliations

1. Department of Hydraulic Engineering Tsinghua University Beijing 100084 China
2. Atmospheric, Earth, and Energy Division Lawrence Livermore National Laboratory Livermore CA 94551 U.S.A.
3. School of Transportation Science and Engineering Beihang University Beijing 100191 China
4. Department of Civil and Environmental Engineering University of California Davis CA 95616 U.S.A., Department of Mechanics, School of Applied Mathematical and Physical Sciences National Technical University of Athens Zographou Campus Athens Greece

Publication Date:

Thu May 11 00:00:00 EDT 2017

Sponsoring Org.:

USDOE

OSTI Identifier:

1401902

Resource Type:

Publisher's Accepted Manuscript

Journal Name:

International Journal for Numerical and Analytical Methods in Geomechanics

Additional Journal Information:

Journal Name: International Journal for Numerical and Analytical Methods in Geomechanics Journal Volume: 41 Journal Issue: 17; Journal ID: ISSN 0363-9061

Publisher:

Wiley Blackwell (John Wiley & Sons)

Country of Publication:

United Kingdom

Language:

English