酸性饱水对砂岩力学参数的损伤效应

The Damaging Effects of Acidic Saturated Water on the Mechanical Parameters of Sandstone

通过对金沙江向家坝水电站砂岩在不同酸性条件、饱水条件的常规三轴压缩试验,重点研究砂岩抗剪强度的损伤规律。试验设计按照pH=2,4,7,饱水时间自然状态、8,20,35,60,100d进行岩样处理。通过三轴压缩试验分析岩石抗剪强度参数变化规律,结果表明:砂岩的内摩擦角和粘聚力随着饱水时间的延长、酸性增强逐渐降低,抗剪强度参数值与饱水时间服从指数变化规律。定义岩石抗剪强度损伤度,长石砂岩内摩擦角最大损伤度为75.96%,粘聚力损伤度为34.41%;石英砂岩内摩擦角最大损伤度为83.57%,粘聚力的损伤度为29.07%。内摩擦角的损伤度明显大于粘聚力的损伤度,内摩擦角更易受到饱水作用的损伤。

Through conventional triaxial compression tests on sandstone under different acidic and saturated conditions in Xiangjiaba hydropower station of Jinshajiang, the damage law of shear strength for sandstone was emphatically studied. The sandstone samples were respectively tested under pH = 2, 4, 7, and saturation period of natural state, 8, 20, 35, 60, 100 days. The variation rules of shear strength parameters were analyzed by triaxial compression tests. And the results showed that, the internal friction angle and cohesion of sandstone gradually decreased with the increase of saturation time and acidity, and the value of shear strength parameters and saturation period complied with the exponential variation. Then, the damage degree of rock shear strength was defined. For feldspar sandstone, the maximum damagedegree of internal friction angle was 75.96%, and the maximum damage degree of cohesion was 34.41%. For quartz sandstone, the maximum damage degree of in- ternal frictionanglewas 83.57 %, and the maximum damage degree of cohesion was29.07%. The damage degree of internal fric- tion angle was obviously larger than that of cohesion, so that the internal friction angle was easier to be damaged under water saturated conditions.