Triaxial test and PFC-FLAC coupling simulation study on material parameters and deformation characteristics of soil-rock mixture

Based on large-scale triaxial test and PFC3D-FLAC3D coupling analysis method, flexible servo triaxial loading models, which restore the actual shape of some large-size stones are established. The deformation and failure characteristics of soil-rock mixture(SRM) specimens and the development law of shear plane and contact force chain are studied. The numerical simulation results show that the triaxial shear process of SRM can be divided into two stages:axial compaction and lateral bulging. The axial compaction stage decreases with the increase of confining pressure, while the radial deformation increases with the increase of confining pressure. The friction angle of SRM increases with the increase of the gravel content, while the change trend of the cohesion is opposite. The impact of rock content on the friction angle and cohesion is about 10%, and rocks mainly enhance the structural of the SRM. X-shaped shear bands are formed in the middle of the sample during failure and lateral displacement mainly occurs in the middle, while the upper and lower ends have tapered elastic areas and vertical displacement mainly occurs. When the axial strain is less than 5%, the coordination number increases with the increase of the axial strain, and the porosity decreases with the increase of the axial strain while the change low is opposite when the axial strain is greater than 5%. With the increase of axial strain, the force chain gradually concentrates to the area with more rocks, and the axial force is mainly provided by the contact between rocks. The normal contact force of particles mainly provides the axial force, while the horizontal force is mainly composed of tangential bonding and friction. © 2021, Science Press. All right reserved.