ANALYSIS OF THE ENERGY RELEASING RATE IN ROCKBURST FAILURE

Rock burst is a sudden and violent failure of overstressed rock resulting in the instantaneous release of large amounts of accumulated energy. The amount and rate of the energy release can dominate the failure process in range and intensity. In this paper, the energy releasing rate in rock tunnel excavation is numerically analyzed based on the complete failure behavior of the rock. The post peak failure characteristics of the rock mass are simulated in the numerical model. In this way, the variation of the elastic energy stored in the rock mass is computed. Furthermore, the amount of the elastic energy and the releasing rate can also be evaluated simultaneously. The paper presents the numerical simulations of over excavation and loose blasting. The numerical results indicate that the risk of rock burst failure can increase if the rock mass is over excavated in tunnel projects. On the other hand, the loose blasting in the whole circular area can effectively reduce such risks. On the contrary, careful consideration should be made to adopt loose blasting in the stress concentrated area because too much reduction of the stiffness of the rock in such an area may unexpectedly increase the risk of rock burst.