单轴压缩下饱水裂隙砂岩体积效应的试验研究

为研究水和岩样体积对砂岩物理力学及变形特性的影响,采用MTS815型岩石力学测试系统,对干燥和饱水状态下的3种不同体积(高径比2∶ 1)完整和裂隙砂岩进行单轴压缩试验。结果表明:完整和裂隙砂岩的孔隙率与饱和吸水率与岩样体积成正比;干燥和饱水的完整与裂隙砂岩单轴抗压强度均随体积增大而小幅降低;砂岩弹性模量和变形模量与岩样体积呈负相关,且水降低了砂岩的弹性模量与变形模量;干燥砂岩的泊松比随岩样体积增加而增大,而饱水砂岩则随岩样体积先增加,后稳定;干燥的完整和裂隙砂岩的宏观破坏形式由小尺寸的轴向多劈裂面破坏逐渐转变为大尺寸的单一剪切破坏,水的存在对岩样单轴压缩破坏形态没有明显影响。

Experimental Study on Volume Effect of Saturated Fractured Sandstone under Uniaxial Compression

To investigate the effect of water and sample volume on the physical, mechanical and deformational properties of sandstone, the uniaxial compression tests on intact and fractured cylindrical sandstone specimens with three kinds of volume but the same height-diameter ratio under dry and saturated conditions were conducted using MTS815 rock mechanics testing system. The results indicated that: the porosity and water saturated absorptivity of these two kinds of sandstone increased with sample volume; the UCS of dry and saturated sandstone with intact and fractured body decreased with volume but with a slight rate; the elastic and deformational modulus of sandstone dropped by a minor range with the increase of volume, and water contributed to the decrease of this two modulus of sandstone; the Poisson's ratio of dry sandstone all climbed with volume while the situation of saturated condition represented a tendency of first rising and then stabilizing; the macro failure type of dry intact and dry fractured sandstone specimens changed with volume from axial splitting failure with several splitting faces to single shear failure, while no evident change of failure mode was observed on uniaxially compressed specimens under dry or saturated conditions.