Stable deformation of rock near deep-level tabular excavations

Abstract

Analysis based on the theory of dislocations can provide a quantitative description of the inelastic deformation that occurs near the edges of thin tabular excavations (stopes) at deep levels in brittle rock. The stope is modeled as an array of edge dislocations that climb from the center of the stope toward the edges as the stope is enlarged. The dislocations representing the stope interact with dislocations representing inelastic deformation in the surrounding rock and with the virgin stress field. One type of interaction leads to the formation of a zone of fractured rock, represented as an array of dislocations extending ahead of the stope. The continuous migration of dislocations into the plane of the stope results in the production of a ‘fracture zone’ and the continuous convergence of the center of the stope. This process consumes much of the energy released by extending the stope, and also relaxes the intense stress field near the edge of the stope.