Experimental Study on the Mechanical Properties and Crack Propagation of Jointed Rock Mass Under Impact Load

Abstract

A drop hammer impact test on jointed rock masses is carried out in this study. According to the analysis of the effect of different joints on the strength, the deformation and the damage of jointed rock masses, the law of the mechanical properties and crack propagation of jointed rock masses is observed under impact load. First, when the dip angle and the number of the joint are greater, the dynamic bearing capacity of rock masses will be weaker. Meanwhile the deformation and the damage of rock masses will increase. Then, when the impact load is small, the dynamic compression deformation of jointed rock mass is mainly due to the normal closure of joints. After the impact load increased, more microcracks are produced around the joints. These cracks will gradually spread along the joints and finally lead to the damage of jointed rock masses. Besides, the joint can increase the stress waves energy dissipation and weaken the propagation of the stress waves in the rock mass. The study provides a reference for the dynamic analysis of fractured rock masses and the excavation support of surrounding rock mass in deep mining of mines.