韧性岩石常规三轴压缩试验及变形与损伤演化规律研究

 利用岩石全自动三轴伺服仪，对向家坝水电站坝基挤压带强风化砂岩进行不同围压下的常规三轴压缩试验，并对岩石变形和破坏机制进行研究。试验结果表明：该强风化砂岩表现出显著的非线性变形和延性破坏特征，属于韧性岩石。在偏压作用下，岩石轴向和侧向应变分别为5%和4%，体积膨胀量为4%以上。岩石变形力学参数随荷载的变化而变化，随偏应力的增大，岩石弹性模量减小，泊松比增大。围压可提高岩石抵抗变形和破坏的能力，围压越大，岩石发生扩容的起始偏应力越大。基于密度方法研究岩石损伤演化规律。加载初期，岩石被压密，处于无损阶段；当偏应力超过一定水平时，岩石出现损伤，且损伤量与等效应变呈线性关系，密度损伤阈值低于0.12。试验结果对向家坝水电站坝基稳定性分析有重要参考价值。

INVESTIGATION ON CONVENTIONAL TRIAXIAL COMPRESSION TESTS OF DUCTILE ROCK AND LAW OF DEFORMATION AND DAMAGE EVOLUTION

The rock sample is strongly weathered sandstone which is from the compressive zone of the dam foundation of Xiangjiaba hydropower station，and the conventional triaxial experiments under different confining pressures are carried out for the rock by using automatic triaxial servo-instrument. The deformation and failure mechanism of rock are studied. The results show that the rock has significant characteristics of non-linear deformation and ductile failure，so it belongs to ductile rock. In the action of deviatoric stress，the axial and lateral strain of rock reaches 5% and 4% respectively，and the volume expansion strain reaches more than 4%.The deformation mechanical parameters of rock change with the loading. With the increase of deviatoric stress，elastic modulus of the rock decreases as well as Poisson?s ratio increases. The confining pressure enhances the rock resistance to deformation and failure. The greater the confining pressure，the larger the initial expansion deviatoric stress of rock. Based on the density method，the damage evolution of rock is discussed. At the initial loading state，the rock is compacted without damage；when the deviatoric stress exceeds a certain level，the rock damage increases as a linear relationship with the equivalent strain，and the density damage threshold is lower than 0.12. The experiment results offer important reference value to the research of stability of the dam foundation of Xiangjiaba hydropower station.