高围压、高水压条件下岩石卸荷力学性质试验研究

 为探悉某深埋长引水隧洞围岩在高地应力、高水压力条件下的稳定性，对隧洞的主要岩体大理岩、砂岩和板岩进行常规三轴压缩试验、峰前峰后卸围压试验以及高水压力下的卸荷试验，对此过程中的强度和变形特征进行较为系统的对比分析研究。研究结果表明：卸围压对岩石的强度影响很大。卸荷后，岩石的黏聚力和内摩擦角均有较大幅度的降低，特别是有水压时，降低更是明显；卸荷对黏聚力的影响比对内摩擦角的影响大。卸荷后，黏聚力的降低幅度比内摩擦角要大；峰前卸荷对岩石强度的影响比峰后卸荷要大。峰前卸荷，岩石破坏时围压比峰后卸荷高；有水压卸荷对岩石强度的影响比无水压卸荷要大。有水压时卸荷，由于水压的存在，削弱围压对岩石的影响，使岩石在比无水压卸荷时更高的围压下即发生破坏。

EXPERIMENTAL STUDY OF UNLOADING MECHANICAL PROPERTIES OF ROCK UNDER HIGH CONFINING PRESSURE AND HIGH WATER

In order to analyze surrounding rock stability of long alignment high overburden diversion tunnel，conventional triaxial compression tests，unloading confining pressure tests at the pre-peak and post-peak and unloading tests under high groundwater pressure on marble，sandstone and slate are conducted. Systematic contrastive studies are made on the strength and displacement in the experiment. The experimental results indicate that unloading confining pressure has important effect on the intensity of rock. The cohesion and angle of internal friction of rock reduce considerably after unloading confining pressure；the reduction is more obvious especially with water pressure. The effect of unloading confining pressure on cohesion is more obvious than that of angle of internal friction. The reduction extent of cohesion is bigger than angle of internal friction after unloading confining pressure. The effect on rock strength at the pre-peak unloading confining pressure is bigger than that at post-peak unloading confining pressure. The confining pressure of rock failure with unloading confining pressure at the pre-peak is higher than at post-peak；the effect on rock strength unloading confining pressure with water pressure is bigger than unloading confining pressure without water pressure. By unloading confining pressure with water pressure，it can weaken the effect of confining pressure on rock，which makes rock failure with higher confining pressure than that without water pressure.