压力水-岩耦合作用下砂岩断口微观破坏机理

为了研究流固耦合作用下岩石的损伤劣化机理，以砂岩岩样为研究对象，采用流固耦合力学实验系统开展轴压水压耦合作用下单轴压缩、三轴压缩及三轴蠕变实验，借助扫描电子显微镜对岩样破裂断口的微观结构特征进行分析。结果表明:单轴饱水岩样破裂断口表面比干燥岩样出现更多的裂纹核，且断口形貌以沿晶断裂为主，穿晶断裂为辅；随着水压增大，三轴压缩岩样破裂断口表面裂纹核逐渐变少，剪切平行裂纹逐渐增多，岩样的宏观破坏形式从以张拉破坏为主逐渐向以剪切破坏为主转变；与三轴压缩岩样断口相比，三轴蠕变岩样破裂断口表面平整度和光滑度较差，晶体间联结更加紧密，剪切裂纹密度和深度增加。

Micro-Damage Mechanism of Sandstone Fracture Under Coupling of Hydraulic Pressure and Rock

The sandstone samples were taken as research objects to study the damage and degradation mechanism of rock under fluid-solid coupling. The fluid-solid coupling experimental system was used to perform uniaxial compression，triaxial compression and triaxial creep experiments under the coupling action of axial pressure and hydraulic pressure. The microstructure characteristics of fractured rock were analyzed by scanning electron microscopy. The results show that there are more crack cores in the fractured surface of the uniaxial saturated rock samples under uniaxial compression compared with the dry rock samples. The fractured surfaces consisted mainly of intergranular ruptures with some transgranular ruptures. With the hydraulic pressure increasing，the crack cores in the fractured surface of the rock samples decrease，and the shear parallel cracks increase gradually under triaxial compression. The macroscopic failure mode of rock samples changes from tensile failure to shear failure. Compared with the rock samples under triaxial compression，the flatness and smoothness of the fractured surface of the rock samples are poorer，the intercrystal connections are more compact and the shear crack density and depth increase under triaxial creep.