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锦屏二级水电站深埋引水隧洞位于高地应力区,对取自隧洞内的大理岩进行常规三轴压缩试验、峰前卸围压试验。基于大理岩的峰前卸荷试验,研究峰前卸荷条件下岩石的变形、参数及破裂特征,建立峰前卸荷条件下岩石的幂函数型Mohr强度准则,给出数值仿真试验中大理岩的峰前卸载条件,利用有限差分程序FLAC3D建立了数值仿真模型,对模型进行了计算与分析,最后与室内试验结果对比,得到峰前卸荷状态下大理岩力学特性的相关规律。研究结果表明,幂函数型Mohr强度准则可较好地反映峰前卸荷条件下岩石的强度特性;卸围压初期,岩石试件呈现出明显的弹塑性特征;卸荷过程中岩石试件发生破坏时的峰值强度和围压降值随着围压增加而变大。研究结论揭示了锦屏大理岩卸载应力路径下的力学特性,具有一定的理论参考价值。
The Jinping II Hydropower Station deep-buried water diversion tunnel is located in the high stress area. The marble taken from the tunnel is subjected to conventional triaxial compression tests and pre-peak unloading confining pressure tests. Based on the pre-peak unloading test of marble, the deformation, parameters and fracture characteristics of rock under unloading condition before peak are studied. The power function Mohr strength criterion of rock under pre-peak unloading condition is established. The numerical simulation results of marble, , The finite element program FLAC3D was used to establish the numerical simulation model. The model was calculated and analyzed. Finally, compared with the indoor test results, the related laws of mechanical properties of marble under unloading condition were obtained. The results show that the power function type Mohr strength criterion can well reflect the rock’s strength characteristics under the unloading pre-peak conditions; at the initial stage of unloading confining pressure, the rock specimens show obvious elastoplastic characteristics; The peak strength and the pressure drop at breakage increase with the increase of confining pressure. The conclusion of the study reveals the mechanical properties under the unloading stress path of Jinping marble and has certain theoretical reference value.