Strength and Deformation Characteristics of Granular Materials under Extremely Low to High Confining Pressures in Triaxial Compression

— The shearing strength and volumetric relationship of granular materials change notably with a variation of confining pressure. In this study the effect confining pressure on the mechanical behavior of granular materials were observed using discrete element method (DEM). The triaxial tests were conducted on seven specimens covering a range from extremely low to high confining pressures. Each isotropically compacted specimen contains similar number spherical particles for same porosity. The strength and deformation characteristics show a good agreement with the experimental behavior of granular materials. At low to high confining pressures, there is a decrease in the peak angle of shearing resistance and dilation with the increase of confining pressures. However, the dependency of peak friction angle, dilatancy index and deformation characteristics on extremely low confining pressures are negligible. A unique relationship was also observed between normalized work and axial strain under different confining pressures. Microscopic parameter such as coordination number increases with the increase of confining pressure both for extremely low and low to high confining pressures. However, the tendency of evolution of the coordination number is quite different in extremely low and low to high confining pressures.