STUDY ON MECHANICAL CHARACTERISTICS AND FAILURE BEHAVIOR OF SOIL-ROCK MIXTURE UPON COMBINED FDEM NUMERICAL SIMULATION

Soil-rock mixtures (SRMs) are often encountered in shallow strata, and their mechanical characteristics will directly affect the stability of these geotechnical projects. The combined finite-discrete element method (FDEM) was used to study the mechanical characteristics and failure behavior of SRM. The two-dimensional FDEM numerical modeling method and parameter assignment method for SRM were proposed. The effects of element size, of rock topology and of rock content on the mechanical characteristics and on the fracture behavior of SRM were also investigated. The results indicate that: the heterogeneous rock sample modeling method based on Weibull distribution can be used to establish an FDEM numerical model of SRM. A numerical model of SRM with different rock contents and topological structures can be built by adjusting the soil-rock boundary x, element size h and control points when building the model; the sensitivity analysis of element size and rock topology verifies the robustness of the modeling method proposed for SRM; the uniaxial and triaxial compression simulation results of samples with different rock contents show that: uniaxial compressive strength, triaxial compressive strength, equivalent elastic modulus, equivalent cohesion and equivalent internal friction angle of the SRM increase exponentially with the increase of rock content; and under the condition of triaxial compression, as the confining pressure increases, the SRM sample develops from single shear crack failure to X-shaped conjugate shear failure, and the value of shear failure angle is consistent with its theoretical one.