Triaxial compression test of coarse-grained soil in waste dump under different consolidation stresses conditions

Abstract

In order to explore the mechanical response characteristics of coarse-grained soil in waste dump under different consolidation stress conditions, the isobaric consolidation drained triaxial test and $K_0$ consolidation drainage triaxial test under different confining pressures are performed, and the test data of stress-strain and volume deformation of soil are compared and analysed. The results show that the initial stress of soil under $K_0$ consolidation condition is not zero. The shear stress-strain curves of soil with different consolidation conditions show hardening characteristics. When confining pressure increases, the shear stress of isobaric consolidated soil increases rapidly, and its failure shear stress increases significantly compared with $K_0$ consolidated soil. Shear expansion of coarse-grained soil under low confining pressure and shear shrinkage under high confining pressure. Under low confining pressure, $K_0$ consolidated soil is more prone to shear expansion, and the amount of shear expansion is greater than that of isobaric consolidated soil. Under medium and high confining pressure, the volume compression change of isobaric consolidated soil is greater than that of $K_0$ consolidated soil. The initial tangent Poisson’s ratio of coarse-grained soil under different consolidation stress conditions decreases with the increase of confining pressure, and changes in a power function with the confining pressure. The cohesion of soil under isobaric consolidation stress condition, while the difference of internal friction angle of soil under different consolidation stress condition is small. The strength and deformation characteristics of soil are closely related to the initial stress state of soil. The triaxial test is used to obtain the shear strength index of soil, and the isobaric consolidation condition should not be used instead of $K_0$ consolidation condition.