SIMULATION OF PROGRESSIVE FAILURE IN HANGING-WALL AND FOOTWALL FOR MINING WITH SUB-LEVEL CAVING

The progressive development of fractures in the hanging-wall and footw all with increase in mining depth in sub-level caving has been numeric ally simulated using a non-linear Coulomb-material model with tension cutoff. The modelling strategy is described in detail. Four model case s are studied that cover high and moderate in-situ stresses, strong an d weak material and orebody dips of 60 and 70-degrees. The numerical s imulation indicated that once a tension fracture initiates on the grou nd surface in the hanging-wall region it grows in an unstable manner i n tension with increasing mining depth and new tension fractures appea r on the surface. The ultimate failure of the wall occurs by collapse into the void created by mining. Tension cracks also develop in the fo otwall, but their growth is stable. The results generated by the numer ical model are compared with actual measurements from two mines in Ind ia and Sweden.