Analysis of stress-induced damage initiation around deep openings excavated in a moderately jointed brittle rock mass.

摘要

his thesis focuses on the understanding of the damage and failure processes in massive to moderately jointed brittle rock masses surrounding deep excavations, and on the development of procedures for enhancing the geomechanical design of these openings.;By carrying out several field observations in deep underground mines and an extensive literature review, this thesis proposes that the damage process in the region of low confinement near openings, subjected to high in situ stresses, starts by the nucleation and propagation of extension fractures within the intact rock material inside the rock mass. Movements of wedges and along pre-existing, generally non-continuous, discontinuities have only a minor effect on the rock mass damage initiation, because they do not initially have the kinematic freedom to move.;This research proposes a basic rock mass damage initiation criterion and validates it by successfully predicting stress-induced damage initiation (DI) zones formed around deep openings excavated in both massive and in moderately jointed brittle rock masses, such as that surrounding the Sudbury Neutrino Observatory (23 m diameter x 30.8 m high, 2070 m deep). The DI zones are predicted by performing elastic numerical analyses and identifying regions where the deviatoric stresses, (;The actual rock mass peak strength