Abstract:

In order to research the development characteristic about crack of smooth blasting under the condition of different coupling medium.The brittle material Von Mises failure criterion was applied and the model of smooth blasting with different borehole spaces and different burdens was established based on ANSYS/LS-DYNA dynamic definite programs smooth blasting crack law under the condition of coupling mediums of air and water.The results found that，as the numerical simulation confirmed，the explosive energy transmitted to rock was different and the development of crack would be influenced due to the two different medium property leading to different coupling mechanisms.The blast-induced crack surrounding the hole and crack bifurcation phenomenon was relatively small and the transfixion crack was formed easily when air as coupling medium.Under the same conditions，the quality of transfixion crack was poor or without significant crack，but the blast-induced crack surrounding the hole was development and with more crack bifurcation phenomenon which was adverse to form the radial crack between the holes.The Von Mises stress relaxation curves between the holes accords with power function relaxation under the condition of two coupling mediums，and the Von Mises hole-wall stress was obviously higher and the relaxation speed was smaller than that of air when the coupling medium was water.The simulation results also suggested that the stress transmitted to rock and blast crack would reduced with the decoupling coefficient，and the effect of smooth blasting was best when the decoupling coefficient is 2.1.

Key words: smooth blasting, decoupling charge, blasting crack, LS-DYNA