Abstract: The geological hazards such as rock burst etc can be induced easily by the stress concentration area of deep deposit, using unloading blasting method to release the excess energy of stress concentration area is helpful for promoting the dynamic balance of whole energy system,the transfer of high stress to deep rock mass,stress redistribution of surrounding rock,so,the final goal of rock burst prevention can be realized.In order to study the influence of deep initial ground stress field to unloading blasting effects,the unloading blasting process of rock mass with three mining depth is simulated by adopting ANSYS/LS-DYNA software.The study results show that,with the increasing of the mining depth from 1 000 m to 3 000 m,the variation scope of the failure area caused by unloading blasting is significant,with the further increasing of initial ground stress, the inhibition effects of ground stress to the failure degree caused by unloading blasting is enhanced gradually,which caused the failure area volume formed by blasting stress wave and blasting gas is decreased significantly,and the volume variation doesn't characterized by monotonicity;the failure type of rock mass caused by unloading blasting is transferred from tensile failure to shear failure,the inhibition effects of ground stress to tensile failure or rock mass is obvious,while the shear failure of rock mass can be promoted by ground stress.The above analysis results can provide some theoretical reference for the unloading blasting design of deep ore-bodies.

Key words: Unloading blasting, Mining depth,Distribution of ground stress, Tensile failure, Shear failure, Numerical simulation