EXPERIMENTAL STUDY ON COEFFICIENTS OF BRITTLE STRESS DROP OF MARBLE

The complete stress-strain curve of rock could be divided into pre-failure and post-failure regions according to the peak stress. The post-failure mechanical characteristics of rock are important to many rock engineering cases,such as underground excavation,pillar,rock burst and so on. Therefore,the research on the post-failure characteristics of rock is of great significance to both theory and practice. In general,the post-failure region of rock shows instability in the mechanical response,which is difficult to be described by the strength softening model;and it should be described by the brittle-plastic model. Taking the axial strain rate as a constant, a series of triaxial conventional compress failure tests of Ya′an marbles were performed by RMT–150B rock mechanics test system;and the complete stress-strain curves of rock specimens under different confining pressurees were obtained. Utilizing the stress-strain curves,the relation functions between brittle stress drop and confining pressure of marble are obtained. The achieved results can provide references,when using brittle-plastic model,to the numerical analysis of marble and its structures as well.