Research on Coefficient of Brittle Stress Drop of Red Sandstone

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 corresponding to a good many rock engineering,such as underground excavation,pillar,rock burst and so on.Therefore,the research on the post-failure characteristics of rock is of important significance both in 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 soften model,and should be described by the brittle-plastic model when the softening rate is relatively great.Keeping the strain rate of axial as a constant,a series of travail conventional compress failure tests about red sandstone of Guixi are performed by RMT-150B rock mechanics test system,and the complete stress-strain curves of rock specimens under different confining stresses are obtained.Utilizing the stress-strain curves,the relation function between brittle stress drop and confining stress of red sandstone was obtained,and the beneficial reference is provided when brittle-plastic model to numerical analysis of red sandstone and its structures as well are applied.