Research on Coefficent of Brittle Stress Drop of Brittle-plastic Rocks

The complete stress-strain curve of rock is divided into pre-failure and post-failure regions according to the peak stress.Because the post-failure mechanical characteristics of rock are corresponding to a good many rock engineering items,such as underground excavation,pillar,rock burst and so on,the research on the post-failure characteristics of rock is of important significance both in theory and practice.In general,the post-failure regions of rock shows instability in the mechanical response,which is difficult to be described by the strength soften model,but can be described by the brittle-plastic model.To keep the strain rate of axial as a constant,a series of triaxial conventional compress failure tests about marble of Ya'an,red sandstone of Guixi and granite of Dawu were performed by RMT-150B rock mechanics test system,and the complete stress-strain curves of rock specimens under different confining stresses were obtained.Utilizing the stress-strain curves,the relation function between brittle stress drop and confining stress of marble was obtained,and the beneficial reference was provided when applied brittle-plastic model to numerical analysis about marble and its structures as well.