酸性环境干湿循环作用对泥质砂岩力学参数的劣化研究

针对降雨和库水位升降对库岸边坡消落带岩体力学参数的劣化问题,选取泥质砂岩进行不同p H水环境干湿循环作用下的单轴与三轴压缩试验,结合室内试验结果,应用广义Hoek–Brown准则求得不同地质强度指标评分(GSI)下岩体的单轴抗压强度、弹性模量、材料常数和黏聚力。研究表明:破碎程度越大的泥质砂岩受浸泡的溶液酸性越强、干湿循环次数越多,其力学参数劣化程度就越高;在同一个GSI评分下,泥质砂岩各个力学参数随p H值和干湿循环次数n的劣化效应排序有所差异,综合劣化效应最大为弹性模量,累积劣化效应最明显为黏聚力,其劣化系数与浸泡溶液的p H值、干湿循环次数的对数ln(n)成线性相关。基于上述研究提出了泥质砂岩力学参数与p H值、干湿循环次数n的三维劣化方程,为酸性环境干湿循环作用下现场岩体力学参数的获取以及边坡稳定性寿命的预测提供了理论依据。

Deterioration of mechanical parameters of argillaceous sandstone under wetting-drying cycles in acidic environment

Considering that the mechanical parameters of rock mass in reservoir slope are degraded by water level fluctuation and acid rainfall, uniaxial and triaxial compression tests are conducted on the argillaceous sandstone under wetting-drying cycles in acidic environment. Based on the laboratory test results, the uniaxial compressive strength, elastic modulus, material constants and cohesion of rock mass in geological strength index (GIS) are obtained using the generalized Hoek-Brown criterion. The results show that the deterioration of the mechanical parameters is more obvious under higher wetting-drying cycle number and more acid solution for the broken argillaceous sandstone. Under the same GSI score system, there are differences in the ordering of deterioration effect for each mechanical parameter with change of pH values and wetting-drying cycle numbers, the elastic modulus belongs to the largest comprehensive degradation effect, and the cumulative degradation effect of cohesion is the most obvious. A strong linear correlation is observed in the deterioration of mechanical parameters of rock mass, pH value of soak solution and logarithm of wetting-drying cycle numbers. Based on the above research, a three-dimensional curved surface equation for the mechanical parameters of argillaceous sandstone, pH value and wetting-drying cycle numbers is put forward, which can provide a theoretical basis for obtaining the mechanical parameters of rock mass under wetting-drying cycles in acidic environment and predict the stability life of the slope.