Deformation and fracturing process of discontinuous rock masses and damage mechanics

A damage mechanics theory for discontinuous rock mass is proposed and applied to an excavation problems of underground cavern of three different shapes for a hydro-electric power station. Distributed joints in rock mass are characterized by a second-order symmetric tensor, called the damage tensor which is evaluated by a technique of three-dimensional photographic surveying with a micro-computer system. Mechanical effects of joints are represented by an additional force vector by introducing the net stress which is derived from the stress vector acting on the effective part of the material body. Results of the damage analysis are compared with those by a conventional analysis, and the influences of joints on the stability of each shaped cavern is checked.