Energy Dissipation Analysis of Dynamic Splitting Damage of Granite by Joint Inclination and Roughness

The Φ50 mm × 25 mm granite with fractal dimension D of 2.0000–2.40376 is loaded by using Φ50 mm split Hopkinson pressure bar system. The influence of joint inclination and roughness on the energy dissipation of granite during dynamic tensile failure is analyzed. The experimental results show that: (1) under the same pressure driving, a sample (D = 2) with θ increases dissipation can be varied as a U-type changes, the minimum value acquired at θ = 30°; (2) the failure mode of single joint specimen has obvious joint direction dependence. With the increase of θ, the failure control mechanism changes: joint plane tension → joint plane shear → rock matrix tension and joint plane shear → rock matrix tension; (3) under the same joint angle θ, the energy absorption (Ws/Wi) of rough jointed rock sample (D > 2) is greater than that of smooth jointed rock sample (D = 2), and the energy dissipation amplitude increases first and then decreases, and the maximum difference is 0.036 at θ = 45°.