Abstract：Based on the experiment results，a surface blasting model of rock with pre-existing defects，including voids，pores and small open joints under blasting loads is established. The defects are randomly distributed，and are empty or saturated with water. A shock equation of state (EOS)，obtained from the existing test results，is employed for the granite near the explosive charge；and for the granite far from the charge，a linear EOS is applied. A modified principal stress failure criterion is applied to determining the granite statuses. The granite dynamic strengths，which increase with the strain rate，are calculated from the existing test results. The simulation results show that：under blasting，as rock contains water，its dynamic strength decreases；the larger the defect density is，the smaller the damage range is. A blasting near a tunnel induces spalling cracks near tunnel free surface easily；and combining with the radial cracks caused during tunnel blasting excavation，the surrounding rock near the tunnel free surface would be cut into a group of blocks which may fall down and may result in rock burst.
ZHU Z M，WANG L，MOHANTY B，et al. Stress intensity factor for a cracked specimen under compression[J]. Engineering Fracture Mechanics，2006，73(4)：482-489.
2011, Vol. 30 
