Microcrack Damage Model of Brittle Rock

摘要

In this report, some extensions and improvements of a recently proposed model which describes stress and time-dependent microcrack growth in brittle rock are discussed. The model is extended to a fully three dimensional description of damage nucleation and growth. In addition, a vectorial description of the damage induced by microcrack growth is proposed. Several improvements in the description of crack growth on the microscale are also discussed. These improvements lead to a development of damage surfaces (surfaces of constant damage in stress space) which is in good agreement with the results of recent experiments in which acoustic emissions were used to trace the progression of damage surfaces in a brittle rock deformed under triaxial compression. Finally, a failure criterion for brittle rock based on the concept of critical damage is proposed and discussed in detail. Several examples of model calculations under a variety of stress states and histories are presented. 27 references, 17 figures. (ERA citation 09:001402)