Micromechanical investigation of soil plasticity using a discrete model of polygonal particles

Abstract

The mechanical behavior of soils has been traditionally described using continuum-mechanics-based models. These are empirical relations based on laboratory tests of soil specimens. The investigation of the soils at the grain scale using discrete element models has become possible in recent years. These models have provided valuable understanding of many micromechanical aspects of soil deformation. The aim of this work is to draw together these two approaches in the investigation of the plastic deformation of non-cohesive soils. A simple discrete element model has been used to evaluate the effect of anisotropy, force chains, and sliding contacts on different aspects of soil plasticity: dilatancy, shear bands, ratcheting etc. The discussion of these aspects raises important questions such as the width of shear bands, the origin of the stress-dilatancy relation, and the existence of a purely elastic regime in the deformation of granular materials.Mehanicko ponasanje tla se tradicionalno opisuje pomocu modela zasnovanih na mehanici kontinuuma. Ove empirijske relacije temelje se na laboratorijskim testovima uzoraka tla. Poslednjih godina postalo je moguce ispitivanje tla na nivou zrna koriscenjem modela diskretnih elemenata. Ovi modeli su omogucili razumevanje mnogih vaznih mikromehanickih aspekata deformacije tla. Cilj ovoga rada je da priblizava dva pristupa istrazivanju plasticne deformacije nekohezivnih tipova tla. Jednostavan model diskretnih elemenata je koriscen u cilju ispitivanja efekata anizotropije, lanaca sile, i kontakata sa klizanjem na razne aspekte plasticnost tla dilatantnost, lokalizacija smicanja raceting, itd. Diskusija ovih aspekata vodi do vaznih pitanja kao sto su sirina pojasa smicanja, razlog za naponsko-dilatantnu relaciju, i postojanje cisto elasticnog rezima pri deformaciji zrnastih (granularnih) materijala.