ISSN 2319-5347, ISI Impact Factor: 0.763

VOLUME 06 NO. 03 JULY 2017:

Title:           Simulation of the Behavior of Granular Materials for Varying Void Ratios using DEM
Authors:     Md. Mahmud Sazzad* , Md. Ahsan Habib
Abstract:    The objective of this paper is to study the behavior of granular materials such as sand under varying void ratios of the samples by two dimensional (2D) discrete element method (DEM) and to quantify the effect of void ratio on different micro-mechanical parameters of granular materials. To achieve the goal, a numerical sample consisting of 8450 ovals was generated in a rectangular frame having a height to width ratio of two without any overlap. The generated sample at this stage was very sparse. Three different samples of different initial void ratios prior to shear were prepared by varying the inter-particle friction coefficient during the isotropic compression stage using the initially generated sparse sample. The initial sparse sample was compressed isotropically to 100 KPa using the periodic boundaries in different stages. The samples were subjected to biaxial shear in strain controlled condition. The simulated data were recorded at required interval and the post analysis was carried out. The simulated macro-mechanical behaviors depict the same qualitative behavior as one observes in laboratory experiments. The work is a function of initial void ratio of the sample prior to shear. However, when the wok is normalized by mean stress, a unique behavior is noticed at smaller strain level regardless of the void ratio of the sample. The evolution of effective coordination number is not much different from that of average coordination number and possesses the same patterns. The evolution of fabric ratio for all contacts does not truly represent the stress-strain behavior, while the evolution of fabric ratio for strong contact represents the stress-strain behavior. A unique correlation between the stress ratio and fabric ratio is observed for small strain level regardless of the void ratio of the sample when the samples are subjected to biaxial shear. However, the same relationship deviates when the strain increases.

Keywords: Plane Strain Compression, Dilatancy Index, Micro Parameters, Discrete Element Method..
Pages:       96-102

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