Modeling Matrix-Supported Rock Behavior Using Biconcave Bonding Model of DEM
Date Issued
2016
Date
2016
Author(s)
Chen, Shi-Feng
Abstract
Former researches of rock materials using numerical simulation are mostly based on elastoplastic theory, because of the microscopic structure and microscopic mechanisms are still under investigating. However, micro-cracks and microscopic structure in rock materials play an important role which affect the mechanisms of rocks extremely. In order to investigate the mechanical behaviors of rock materials from microscopic perspect, discontinuum analysis – distinct element method is an effective and appropriate way to reach it. Currently, PFC (particle flow code) is a software that widely-used in rock mechanics based on distinct element method. In this software, “parallel bond model” is designed to describe rock particle cementation. However, parallel bond model is too simplified and unreliable to represent the mechanical behaviors of rock materials appropriately. Thus, Chiu (2014) developed a new model to describe rock particle cementation – Bicocave bond model (BCB), which improve the rock material mechanical behavior by two factors – basis of mechanic and geometric factors. In the improvement of material mechanical behavior, follows the elastic solution of Dvorkin theory. In the improvement of geometric factor, assumes the rock materials are composed of particles with different sizes, the shape of cement between particles are biconcave which allowed to set up between separate particles. Thus, this study performe a series of analysis and investigation using biconcave bond model, and compare with parallel bond model simultaneously. First of all, this study investigate the effects bwtwen microscopic parameters and microscopic behavior through simple model test, and discuss the characteristic of these two maodels. Moreover, this study investigate the relationship bwtwen microscopic parameters and macroscopic behavior by simulating the plane strain test which published by Tsai(2015).Through the results of simulations, this study compares the pros and cons of these two bonding model. And establish a procedure to determine the microscopic parameters of biconcave bond model. Finally, this study simulate the sandstones which includes different kinds of microscopic structure and properties. Propose a standard to set up microscopic parameters through macroscopic behavior in biconcave bond model, which is able to simulate and predict rock mechanics more efficiently.
Subjects
Rock material
microscopic structure
Distinct element method - Particle flow code (PFC)
Discrete element method (DEM)
Biconcave bond model (BCB)
Type
thesis
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