Dynamic Caustics Model Experiment of Blasting Crack Propagating on Joint Rock

The blasting processes of rock with joints,which had different separation angles between the initial crack and joint plane,were studied using the dynamic caustic experiment and PMMA model.The evolution of dynamic intensity factor in the crack-tip field was studied in experiment.And the mechanism of crack propagation while the crack runs through the joint plane was analyzed.In addition,the crack propagating speed was obtained as well.The experimental results show that the dynamic intensity factor at the crack-tip and the propagating speed decreased dramatically while the cracks propagated through joint plane,but afterwards,the intensity factor enhances.When the crack runs through the joint plane,it would deviate a short distance along the joint,and it would continue to propagate in its initial direction.The results of the present research can provide the theoretical basis about the blasting fracture of rock mass with joints.