Comparing the Behavior of Dense Sandy Soils Inside and Outside the Shear Band in the Direct Shear Test Using the Two-dimensional Discrete Element Method

Document Type : Research Article

Authors

1 Yazd University

2 a department of Civil Engineering, Yazd university, Yazd, iran

3 Department of Civil Engineering, Yazd University, Yazd, Iran

Abstract

Shear banding is one of the most significant behavioral characteristics of granular soils, which is actually the result of localization of deformations under loads applied to the soil sample. Many studies have been conducted on the phenomenon of shear band formation. However, the comparison of the behavior of soil inside and outside the shear band has received less attention. The purpose of this study is to compare the behavior of soil inside and outside the shear band in the direct shear test at macro and micro scales using the two-dimensional discrete element method. To achieve this, the micro-material parameters were first calibrated through the comparison of simulation and experimental results. Then a parametric study was conducted by performing 9 direct shear tests with different vertical stresses on three soil samples with different relative densities. During the tests, quantities such as shear stress, porosity, particle rotation, coordination number, and interparticle plastic energy were measured both inside and outside the shear band. The results of the present study showed that the particle rotations at the end of the test inside the shear band were 5 to 17 times higher than those outside the shear band. Furthermore, the results showed that the dissipated energies at the end of the test inside the shear band were 12 to 96 times larger than those outside the shear band. Moreover, it was found that the coordination numbers at the end of the test inside the shear band were on average 3-19% lesser than those outside it.

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