红砂岩应力脆性跌落系数的试验研究

岩石的应力—应变全过程曲线以峰值应力为界,通常分为破坏前区和破坏后区两部分。由于岩石破坏后区的力学特性对诸多岩石工程,如地下巷道、矿柱和岩爆等具有重要的工程意义,因此,此方面的研究已受到理论界和工程界的重视。岩石的破坏后区一般处于非稳定状态,当软化速率较大时,其力学响应用经典的应变软化模型来模拟计算难以收敛,而可以考虑采用脆塑性模型。使用RMT-150B型岩石力学试验系统,在轴向应变率保持为常数的条件下,对贵溪红砂岩进行了常规三轴压缩破坏试验,得到了不同围压下岩石的应力—应变全过程曲线。利用试验得到的应力—应变全过程曲线,得到了红砂岩的应力脆性跌落系数与围压的关系表达式,为采用非理想脆塑性模型对红砂岩介质及其中的构筑物进行数值分析提供了依据。

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.