Micromechanical behavior of granular materials under monotonic loading: Numerical simulation using discrete element method

摘要

Engineering behavior of soils is conveniently being expressed in terms of continuum parameters such as stress and strain even though soil is essentially a particulate system. There has been a great effort in the recent past towards establishing stress-strain relations based on principles of continuum mechanics with the ultimate objective of solving boundary value problems in geomechanics. The continuum mechanics models have been largely extended to be suitable for pressure dependent behavior of particulate systems such as soils. However these continuum models do not offer complete physical insight into the behavior of granular materials. Due to its inherent granularity, some features of sand behavior are difficult to understand or model from continuum mechanics principles. An alternative approach that offers a better understanding of granular materials is to treat the material as an assemblage of particles interacting through contact forces. Significant attempts have been made in the recent years in this direction to describe the response of granular materials from micromechanical approach (Chang et al., 1997). Development of numerical tools such as Discrete Element Method (DEM) by Cundall and Strack (1979), which can handle interaction of particles, has made it possible to derive detailed microscopic information and to study the evolution of various microparameters during loading. In this paper, results of monotonic biaxial shear tests on uniformly graded 2-dimensional assembly of 1000 discs under drained conditions are presented.