ELASTIC-MATERIAL CONSTANTS FOR ISOTROPIC GRANULAR SOLIDS WITH PARTICLE ROTATION

The granular material perceived as a collection of particles is modelled as a micropolar continua taking account of particle interaction and microstructure of the material. Explicit expressions of constitutive constants in terms of elastic inter-particle stiffness are derived for granular solids with isotropic random fabric distribution. Based on the derived expressions for isotropic material, six material constants are identified instead of two constants used in conventional elasticity. The derived constitutive constants in explicit terms of inter-particle contact properties provide a fundamental understanding of these constants and furnish useful inter-relations among these constants. The physical meaning of these material constants is discussed with emphasis on the role of particle spin. Finite element analysis incorporating these material constants is described and used to obtain solutions for boundary value problems. Examples are given for granular solids under boundary pressure to show the effects of inter-particle properties and material constants on the behavior of stress distribution and deformation in granular material.