酸性环境干湿循环对泥质砂岩力学特性影响的试验研究

由于库水位升降及降雨等原因，岩体经常处于干湿交替状态，对岩体工程的长期稳定性不利。以三峡库区泥质砂岩为研究对象，进行了酸性环境干湿循环交替作用后的常规单轴与三轴压缩试验研究，获得了泥质砂岩在酸性溶液浸泡干湿循环后的相关力学参数。相对于没有经过干湿循环作用的干燥试件，经过不同次数的干湿循环作用后，泥质砂岩的弹性模量、单轴抗压强度、黏聚力与内摩擦角都有不同程度的降低。各个力学指标的总体变化趋势是在第一次饱水之后有大幅度的降低，此后随着干湿循环次数的增加其降低的幅度逐渐减小。同时，酸性溶液的pH值对力学指标的影响很大，存在对泥质砂岩力学性能影响较大的一个临界pH值，低于此值酸性溶液对泥质砂岩力学性能影响显著增大，高于此值酸性溶液对其力学性能影响较小。

Experimental study of mechanical properties of argillaceous sandstone under wet and dry cycle in acid environment

Due to reasons such as the reservoir water level fluctuation and rainfall preliminarily, alternate wetting and drying usually occurred in the rock, which is fairly harmful for long term safety of rock. Taking argillaceous sandstone in Three Gorges Reservoir area as the research object, the conventional uniaxial and triaxial compression tests after the action of wet and dry cycle in acid environment, have been conducted to obtain the relevant mechanical parameters of the argillaceous sandstone in wet and dry cycle of acid environment. Relative to the dry specimen without dry-wet cycle, there are different degrees of reduction in elastic modulus , uniaxial compressive strength ,cohesion and internal friction angle of argillaceous sandstone with different times of dry-wet cycle. Overall trends of substantial decrease of various mechanical in dices appears, at which saturated with water for the first time, then the decrease of amplitude reduces with the increase in wet and dry cycles. Meanwhile, the pH value of acid environment has a great influence on the mechanical properties; there is a critical pH value influencing the mechanical properties of argillaceous sandstone. The influence of acid environment on mechanical properties of argillaceous sandstone significantly increase in the case below this critical value, there is smaller influence on its mechanical properties when the pH value is higher than the critical pH value.