Quantification of rock mass degradation using micro-seismic monitoring and applications for mine design.

摘要

This thesis addresses issues related to the identification and quantification of rock mass damage and degradation from micro-seismic monitoring information, the strength of moderately jointed, hard brittle rock masses for the purpose of excavation design, and the impact of shear loading on the stability of a degraded rock mass. These issues are studied by means of a numerical experiment on a rock sample with heterogeneous properties, by relating micro-seismic and stress cell measurement data from the Mine-By Tunnel experiment at the Underground Research Laboratory (URL) of Atomic Energy of Canada Ltd. (Manitoba) and the history of progressive disintegration and failure reported at the Lac Shortt Mine (Québec).; The basic principles of brittle rock damage including the initiation, propagation, interaction and coalescence of cracks or fractures provide the background for the development of two new seismic damage indices to spatially outline and quantify the intensity of rock mass degradation.; 2D numerical simulations of the Mine-By Tunnel experiment, in a massive rock mass at the URL, show that clustering events can be related to the spatial extent of yield around the forming notch (overbreak). A 3D elastic model including the progressing notch geometry provides the best estimate of the measurements recorded at stress cells in the roof and floor of the tunnel.; Three stoping case histories from the Lac Shortt Mine further demonstrate the validity of the new seismic damage indices for rock mass failure assessment in a mining situation. These case studies also confirm the applicability of the bi-linear failure criterion for a moderately jointed, hard brittle rock mass.; In summary, this work introduces two new seismic damage indices that produce valuable additional information from measurements obtained by existing seismic networks at little additional cost. The enhanced knowledge of the extent and intensity of the rock mass degradation has been used in the interpretation of the failure processes in massive rock at the Mine-By Tunnel experiment of the URL and in a moderately jointed rock mass at the Lac Shortt Mine. The Lac Shortt case histories also highlight the significant impact of shear loading on the stability of a hard brittle rock mass that has been degraded by mining stresses. (Abstract shortened by UMI.)