Abstract
Many of geotechnical engineering problems arising from particle crushing have been identified under high earth dams and the tips of pile foundations where extremely high pressures exist. Particle crushing causes a change in initial soil structure, resulting in remarkable influence on the compressive and shear behavior of granular materials. In order to investigate the soil behavior associated with the particle crushing in detail, three types of tests were carried out using newly-designed high pressure true tri-axial compression apparatus with capacity of maximum stresses up to 200MPa. High pressure compression test was conducted on Toyoura sand with a variety of stress paths taking into account of an assumption of the actual stress state under the tips of pile foundations. The occurrence of particle crushing was confirmed by showing the particle size distribution curve derived from the sieving test before and after three types of tests. The crushing degree after the shear compression test was found to be significantly higher than other tests. The plastic work calculated from the results of stress-strain relationship and the relative breakage, Br, can be approximately linearized. Furthermore, particle shape analysis was carried out using digital microscope and image analysis software. The difference in appearance and shape of sand before and after test was remarkable.
