Micro-scale behavior of granular materials during cyclic loading--颗粒学报PARTICUOLOGY

Sazzad, Md. M. (2014). Micro-scale behavior of granular materials during cyclic loading. Particuology, 16, 132–141. https://doi.org/10.1016/j.partic.2013.12.005

Micro-scale behavior of granular materials during cyclic loading

Md. Mahmud Sazzad^*

Department of Civil Engineering, Rajshahi University of Engineering & Technology, Rajshahi 6204, Bangladesh

10.1016/j.partic.2013.12.005

Volume 16, October 2014, Pages 132-141

Received 26 October 2013, Revised 17 December 2013, Accepted 20 December 2013, Available online 14 March 2014.

E-mail: mmsruet@gmail.com

Highlights

• The simulated stress–strain–dilatancy behaved qualitatively similar to that of sands.

• The stress–dilatancy relationship depended significantly on confining pressures during unloading.

• Evolution of coordination number depended on both confining pressures and cyclic loading.

• Microtopology of granular materials was significantly affected by the cyclic loading.

• A strong correlation between the macro- and micro-quantities was observed.

Abstract

This study presents the micro-scale behavior of granular materials under biaxial cyclic loading for different confining pressures using the two-dimensional (2D) discrete element method (DEM). Initially, 8450 ovals were generated in a rectangular frame without any overlap. Four dense samples having confining pressures of 15, 25, 50, and 100 kPa were prepared from the initially generated sparse sample. Numerical simulations were performed under biaxial cyclic loading using these isotropically compressed dense samples. The numerical results depict stress–strain–dilatancy behavior that was similar to that observed in experimental studies. The relationship between the stress ratio and dilatancy rate is almost independent of confining pressures during loading but significantly dependent on the confining pressures during unloading. The evolution of the coordination number, effective coordination number and slip coordination number depends on both the confining pressures and cyclic loading. The cyclic loading significantly affects the microtopology of the granular assembly. The contact fabric and the fabric-related anisotropy are reported, as well. A strong correlation between the stress ratio and the fabric related to contact normals is observed during cyclic loading, irrespective of confining pressures.

Graphical abstract

Keywords

Cyclic loading; Confining pressure; Micro-scale behavior; Granular matter; Fabric measures

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