不同卸荷路径下的页岩蠕变特性试验研究

地下硐室围岩流变现象显著,对硐室开挖与运营造成巨大威胁。以某深埋矿井巷道页岩为例,参照地下硐室实际开挖情况设计轴压与围压等比卸荷应力路径,同时开展恒轴压卸围压、等比卸荷两种应力路径下的蠕变试验,研究页岩在不同卸荷路径下的蠕变力学特性。试验发现：(1)页岩在两种卸荷路径下的蠕变特性十分明显,轴向应变量值始终高于侧向应变；(2)岩石在破坏应力水平下的轴向应变增长程度小于侧向应变,岩石的侧向扩容较为明显；(3)等比卸荷和恒轴压卸围压条件下的岩石长期强度分别为47.69MPa和62.85MPa,等比卸荷应力条件下岩石更易屈服破坏。研究成果可为地下硐室长期稳定性研究提供一定参考。

Experimental study on creep characteristics of shaleunder different unloading paths

The rheology phenomenon of surrounding rock of underground cavern is significant, which poses a great threat to the excavation and operation of cavern. Taking a deep mine roadway shale as an example, according to the actual excavation situation of underground chamber, the equal ratio unloading stress path of axial pressure and confining pressure is designed. At the same time, creep tests under constant axial pressure unloading confining pressure and equal ratio unloading stress path are carried out to study the creep mechanical characteristics of shale under different unloading paths. The experimental results show that: (1) the creep characteristics of shale under two unloading paths are very obvious, and the axial strain is always higher than the lateral strain; (2) the axial strain growth of rock under failure stress level is less than the lateral strain, and the lateral dilatation of rock is more obvious; (3) the long-term strength of rock under constant axial pressure and constant unloading confining pressure are 47.69mpa and 62.85mpa respectively, Under the condition of equal unloading stress, the rock is more prone to yield failure. The research results provide a reference for the long-term stability research of underground cavern.