Dynamic responses and failure behavior of jointed rock masses considering pre-existing joints using a hybrid BPM-DFN approach

Numerous joints are often randomly distributed in strata, which can affect the mechanical behaviour of rock mass. The jointed rock mass at a large scale is modeled by the combined technology of the bonded particle model (BPM) and discrete fracture network (DFN). Then, the SHPB system is mimicked through the BPM to provide the dynamic disturbance. The effect of joint geometric parameters on the dynamic responses and failure behaviors of the jointed rock mass were symmetrically investigated. The numerical results exhibit that the dynamic strength decreases with the increase of joint intensity or joint length, however, with different functional relationships. Furthermore, when the average angle of the joints is an independent variable, the average angle will significantly affect the dynamic strength except for the case of deviation angle φ = 90°. When the deviation angle is an independent variable, the dynamic strength is also significantly affected except for the case of average angle θ = 45°. The failure modes are also closely related to the joint intensity, joint length and joint orientation, which are dominated by the X-shaped failure mode. A dynamic strength model is proposed based on the classical Hoek-Brown failure criterion, which is verified by the numerical results with different joint intensities.