Numerical Simulation on the Millisecond Blasting for Deep Boreholes Under the Condition of One Horizontal Free Surface

Aim To investigate the mechanism of the millisecond blasting for deep boreholes under the condition of one horizontal free surface.Methods\ Numerical simulation on the millisecond blasting for deep boreholes with one horizontal free surface was conducted using the dynamic nonlinear finite element method. The movement of rock mass and its damage form in the cave were analyzed based on numerical results.Results\ The rock damage near the bottom of boreholes was mainly in the form of shock compression, near the free surface in the form of spallation. Conclusion\ The blasting action of cut holes and delay time are important factors affecting millisecond blasting, the constitutive behavior of brittle rock is described well using the elastic plastic model with oriented cracks.