Fabric-Stress-Deformation Relations in Granular Materials
Abstract
The basic aims of this research program have been to study the mechanical properties and constitutive relations of granular materials that support the applied loads through interparticular frictional contacts, and to relate these to the granular fabric, both stress-induced and inherent. To this end a coordinated experimental and theoretical program was followed to identify the following: (1) effective parameters that measure the fabric of granular masses; (2) the difference between inherent and induced fabric, and the influence of each on the constitutive response of the material; (3) parameters which measure the evolution of fabric in the course of a given overall load or deformation history; (4) the relation between fabric and the overall stress and deformation; and (5) constitutive relations which directly involve fabric measures and the measure of their evolution, and hence, are based on the fundamental microstructural events which give rise to nonlinear material response. The experimental work included tests on large hollow cylindrical samples of granular materials (sands), where a true three-dimensional stress state could be produced in the sample and accurate measurements of forces and associated displacements could be made. Parallel to this, a series of model experiments on two-dimensional photoelastic rods with oval cross section also was performed. By means of photoelastic procedures, the history of the evolution of the microstructure was recorded for simple shear loading paths. Using the existing image analysis facilities, the photoelastic pictures were analyzed, and major microstructural features were identified and were related to the overall stress and deformation histories using stereological techniques as well as direct measurement of fabric parameters. The experimental studies were closely coordinated with the micromechanical modeling.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1991
- Accession Number
- ADA247009
Entities
People
- S. Nemat-nasser
Organizations
- University of California, San Diego