Abstract: The mechanical properties of coarse-grained materials are closely related to material state, such as confining pressure, density, lithology, gradation, etc. The effect of material state on mechanical properties of coarse-grained materials is investigated by large-scale triaxial tests under isotropic consolidation and drained shear conditions. Test results show that the strain hardening and shear contraction are strong at small dry density. Softening and dilatancy are become stronger as dry density increases. Lithology also has significant effect on mechanical properties of coarse-grained materials. The strain softening and dilatancy are stronger when the lithology is stiffer. Gradation has important effect on mechanical properties of coarse-grained materials. Under same coarse sand and fine gravel content, the coarse-grained material has small strength and big dilatancy for small content of coarse gravel. The void ratios of specimens of different confining pressures are tend to their critical void ratios and show a good linear relationship in logarithmic coordinate system of average normal stress. The normalization of Rowe dilatancy model parameter is good for influence factors of material state, such as confining pressure, density, lithology and gradation, which means the Rowe dilatancy model can well reflect the effect of material state on mechanical properties of coarse-grained materials.

Key words: coarse-grained materials, large-scale triaxial test, mechanical property, material state, confining pressure, density, lithology, gradation