Numerical Simulation of Karst Effect on Slope Stability under Blasting

The slope stability is bound to be affected in the blasting process of open-pit mine, especially when the slope is in the karst area. In order to study the influence of karst on slope stability under blasting and based on Tangya limestone mine slope project, this paper takes the exposed karst at the 1014 m platform of the mine as the research object, and uses ANSYS/LS-DYNA finite element analysis software to conduct numerical simulation. Considering the effect of blasting vibration, the stress distribution of the surrounding rock is obtained, and the effects of blasting on slope stress, vibration velocity, rock damage and effective stress of slope with or without karst cave are compared. The results show that the force of the bench changes and stress concentration occurs for several times due to the existence of karst caves, but the stress value generated by the bench loads is only 7.6 MPa, which still cannot reach the degree of rock mass destruction. For monitoring points at different spatial locations, the difference of vibration velocity becomes larger due to the existence of karst caves, and the vibration velocity in the vertical direction changes more than that in the horizontal direction. In particular, the spatial locations of the monitoring points near the slope edge are more sensitive to this situation. The vibration velocity difference of the monitoring points on the slope edge is about 1 cm/s at most, which does not exceed the allowable vibration velocity. In the process of increasing blasting times, the damage inside the rock mass is also gradually increasing, and the damage is more obvious under the influence of karst caves. The larger the radius of karst area, the more blasting times, the more serious the damage. Compared with previous uniaxial compressive strength experiments, it is found that although the existence of karst caves will cause the change of stress value and stress concentration phenomenon, the peak effective stress generated is far lower than the uniaxial compressive strength of rock mass. In view of the influence of blasting process on slope stability, the support treatment measures of slope in karst area are put forward.