考虑水-力耦合和不同应力路径的砂岩卸荷力学特性试验

为研究不同渗透压力条件下的岩石卸荷力学特性，选取砂岩为研究对象，开展了不同渗透压力和不同应力路径下的三轴卸荷试验，并与常规三轴试验进行对比，比较了不同应力路径下的岩石强度特性，分析了渗透压力对岩石变形和强度参数的影响。试验结果表明：渗透压力的增大会弱化岩石强度，岩石的峰值强度随渗透压力的增大而降低，而轴向变形随渗透压力增大而增加，渗透压力越大，岩石的压密段特征越明显；针对两种不同的卸荷应力路径，恒轴压卸围压路径条件下，岩石的黏聚力不断降低，内摩擦角不断增加，而加轴压卸围压路径条件下，岩石的黏聚力不断增加，内摩擦角逐渐降低。

Experimental study on unloading mechanical characteristics of sandstone considering water-mechanical coupling and different stress paths

In order to study the unloading mechanical properties of rock under different seepage pressures, this paper selects the sandstone as the research object, conducts triaxial unloading tests under different seepage pressures and different stress paths, and compares the results with conventional triaxial tests. The rock strength characteristics under different stress paths are compared, and the effect of seepage pressure on the rock deformation and strength parameters is further analyzed. The test results show that the increase of seepage pressure will weaken the rock strength, the peak strength of rock decreases with the increase of seepage pressure, and the axial deformation increases with the increase of seepage pressure. Aiming at two different unloading stress paths, under the condition of constant axial pressure and unloading confining pressure, the cohesion of rock keeps decreasing and the internal friction angle increases; under the condition of increasing axial pressure and unloading confining pressure, the cohesion of rock keeps increasing and the internal friction angle decreases.