Abstract:
Sandstone, marble, and granite are used to make layered composite rock mass with 6 different combinations. The split Hopkinson compression bar test system is used to conduct dynamic impact tests on layered rocks with different combinations, and high-speed cameras are used to record their failure forms. , analyze the dynamic fracture mode, wave impedance effect and energy dissipation law of composite rock materials, use the discrete lattice spring model to simulate the dynamic fracture process of composite rock specimens, and analyze the stress wave propagation characteristics and stress and damage evolution laws of composite specimens. The research results show that the dynamic fracture characteristics of composite rock materials are related to the upper and lower layer materials. When the dynamic crack initiation toughness of the lower layer material is low, the time from crack initiation to propagation to the rock cementation surface is short. The higher the density of the upper layer material, the better the stress conduction effect, while the greater the density difference between the lower layer material and the upper layer material, the greater the stress difference between the upper and lower ends of the cementation surface; Affected by the wave impedance effect, the stress wave propagation behavior of the composite rock specimen is significantly different. The larger the wave impedance is, the faster the stress wave propagates, the larger the transmission coefficient, and the more transmission energy is generated; The higher the density of the upper layer material, the smaller the density and fracture energy when dissipating energy, and the larger kinetic energy is obtained when the specimen is completely broken; the larger the defined combination coefficient ξ, the earlier the crack initiation time of the specimen, The lost kinetic energy curve and the damage rate curve are more uniform, and the lost kinetic energy peak value is larger.