Visualization study on stress evolution and crack propagation of jointed rock mass under blasting load

In this study, the simultaneous observation of stress wave propagation and crack propagation was realized through the wave-crack synchronous test, which clarified the stress wave propagation and superposition process of rock blasting with jointed rock. The variation law of crack dynamic parameters (stress intensity factor and propagation velocity) was also revealed. On this basis, numerical simulation study was performed using the CDEM method to analyze the influence mechanism of joint length and in-situ stress condition on the blasting stress evolution and crack propagation. The results showed that the joint had significant effect on the distribution state, the evolution law and the propagation process of blasting crack. The blasting stress wave diffracted from the joint end, propagated along the joint plane and superimposed, causing the stress concentration and crack initiation and propagation at the joint end. The longer the joint length, the longer the diffraction time and propagation time of the blasting stress wave along the joint plane. In addition, the biaxial equal in-situ stresses inhibited the propagation of the blasting crack. The inhibition effect was significantly strengthened with the increase in in-situ stress, while it promoted the initiation and propagation of the blasting crack in the middle of the joint.