Numerical Simulation Of Rock Mass Blasting Effect Under High Stress

With the increasing demand for energy and increasing the mining intensity, shallow resources are reducing day by day, so the mines both at home and abroad have entered the extraction state of deep mine resource. When blasting is carried out in deep rock mass at a high geostress environment, the high geostress and explosive blast wave interact with each other to lead the failure process of rock blasting more complex, which result in the differences of the rock blasting effect between considering initial stress and not considering initial stress. In this paper, aiming at this phenomenon, effects of initial stress on blasting and effects of some design parameters of blasting on rock mass blasting are analyzed by applying the finite element software ANSYS and explicit dynamic finite element system LS-DYNA to simulate the deep rock blasting process under high stress.The contents in this paper are concluded as follows:(1) Through studying rock blasting mechanism and the rock dynamic problems under explosion dynamic load, causes of failure process of rock and effects on rock mass strength of strain rate in each failure region are analyzed.(2) The forming and developing process of crush zone, crack area, blasting crater during blasting are researched as well as the variation of pressure stress field and Mises effective stress field by using dynamic finite element software LS-DYNA and ANSYS finite element program to simulate the blasting with single spherical charge for considering initial stress. Comparing the blasting effect for considering initial stress with the blasting effect for not considering initial stress, the results show that the initial stress has a certain influence on extension length, extension direction and quantity of the rock mass crack around the hole, the size of blasting crater and surrounding rock stress field after the explosion.(3) The influence laws of the value of initial stress and ratio of the two directions on the rock mass crushing zone and surrounding rock stress field have been achieved through comparing the numerical simulation results for rock single hole blasting with different bidirectional initial stress by the explicit dynamic method. The result shows that when carrying on blasting design of deep rock mass, spacing between blast holes should be reduced and spacing between blast holes should smaller in the direction of smaller initial stress.(4) Rock blasting process with different parameters (resistance line, detonation mode, blockage) in the condition of initial stress existing has been studied. The results indicated that initial high stress may influence stress field, crack distribution, blasting crater shape and size in various degree.These studying results above will provide a reference for blasting design of deep rock mass.