Numerical Simulation Study on the Mechanism of Blast-induced Crack Propagation of Fractured Rock Mass.

To study the crack propagation mechanism of jointed rock mass under pre-split blasting, LS-DYNA software was used to carry out numerical simulation of rock mass blasting with vertical single joint, horizontal single joint and vertical parallel joint. The influence of in-situ stress was discussed. The results show that when there is a vertical single joint in the center of the blastholes, the cracks between holes can be penetrated. The joints have a tendency to close, and the joint is conducive to improving the degree of rock fragmentation between holes. When there is a vertical parallel joint in the center of the blastholes, the wing crack at the joint tip can be penetrated, but good fragmentation effect of rock cannot be achieved between parallel joints. When the horizontal joint is close to the blast hole, more tensile cracks will occur when the stress wave transmits to the back burst side of the joint surface. When the horizontal joint is far from the blasthole, the blocking effect of the joint is obvious. Under the action of hydrostatic in-situ stress, the initiation and propagation of radial tensile cracks and tip wing cracks are restrained. Under the action of non-hydrostatic in-situ stress, the crack growth is more restrained in the direction of the minimum principal stress, and the restraining effect increases with the increase of the maximum principal stress. [ABSTRACT FROM AUTHOR]