Numerical simulation of rock bursts

Abstract

The mathematical description of dynamic fracture processes, in particular of rock bursts in hardcoal mining, can be advanced by the use of dynamic iterative methods. From a comparison of two different numerical approaches the dynamic finite difference method as used in the FLAC program turned out to be the most suitable. For proper calculation of rock bursts one has to consider, besides a shear break criterion, the simulation of the triaxial, post-failure mechanisms of coal and rock strata as well as the behaviour of contact planes between coal and rock strata.

The results of laboratory drilling tests on triaxial loaded coal samples have been used for this. To understand the genesis of rock bursts lateral inhomogenities either in the seam or at the interface must be taken into consideration as well. If all of these parameters are not included in the model no dynamic fracture processes similar to rock bursts will occur. This also explains the unpredictable nature of rock bursts a rock burst will not necessarily occur when specific relationships between area being worked, geometry, stress and strength exist.