深埋锦屏大理岩力学特性与能量演化研究

与浅层岩体相比，深层岩体赋存环境更为复杂，导致其力学特性与常见的浅部岩体存在较大差异。锦屏二级隧洞工程最大埋深超过2 500 m，其引水隧洞最高地应力达70 MPa，开展高应力条件下硬岩的力学特性研究，具有重要的理论价值和现实意义。采用四川大学MTS815岩石力学试验系统对取自2 400 m深的锦屏大理岩开展单轴和三轴压缩等系列静态力学试验。试验结果表明:锦屏大理岩的单轴抗压强度为180.43 MPa，随围压的增长，大理岩表现出“脆-延-塑”力学特征，围压32.0 MPa为分界点；同时，起裂应力、损伤应力和峰值应力均具有相似的增长趋势，所定义的脆性指标的下降趋势逐渐趋于平缓；低围压下，弹性能在峰前占主导，而高围压下，耗散能增长更为显著，弹性能峰前峰后差值减小，表现出更为明显的塑性特征。研究结果为准确描述深层岩石力学行为、确保深部工程稳定性提供了一定的理论基础。

Study on mechanical properties and energy evolution of Jinping deep buried marble

Compared with shallow rock mass, the occurrence environment of deep rock mass is more complex, which leads to the great difference between theri mechanical properties. The maximum buried depth of the tunnel in Jinping II hydropower station is more than 2 500 m, and the maximum ground stress of diversion tunnel is 70 MPa. It is of great theoretical value and practical significance to study the mechanical properties of hard rock under high stress conditions. Therefore, a series of static mechanical tests, including uniaxial and triaxial compression tests, were carried out systematically on Jinping marble from 2 400 m depth by MTS815 rock mechanics test system of Sichuan University. The test results show that the uniaxial compressive strength of Jinping marble is 180.43 MPa. With the increase of confining pressure, the marble shows the mechanical characteristics of “brittle-ductile-plastic” transformation, and 32.0 MPa is a demarcation point. At the same time, there are similar growth trends between the crack initiation stress, crack damage stress and crack peak stress, and the decreasing trend of the brittleness index is gradually flattened. Under low confining pressure, the elastic energy is dominant before the peak, while under high confining pressure, the dissipative energy increases more significantly, and the difference between pre-peak and post-peak elastic energy decreases, showing more obvious plastic characteristics. The research results provide a theoretical basis for accurately describing the mechanical behavior of deep rock and ensuring the stability of deep engineering.