Development of a Biaxial Compression Test Apparatus for Granular Materials

摘要

A set of two-dimensional biaxial compression testing system was developed to investigate the stress-strain behavior and its change with the micro-structure of granular materials. The specimen was assembled using small metal bars with elliptical section. Load was then subjected in both horizontal and vertical directions. Three different stress paths could be realized, including constant lateral pressure, constant mean principal stress and constant principal stress ratio. A non-invasive measurement method using digital image correlation analysis was developed. The displacement of each particle in the specimen could be traced. As a result, the displacement field of each specimen and its micro-structure evolution during loading process could be measured. The testing system was applied in monotonic shear tests for two-dimensional assemblies of metal bars with different size, showing its essential effectiveness for the investigation of the micro-structure change and mechanical behavior.