论文部分内容阅读
针对周期性干湿循环作用下岩石损伤劣化问题,以三峡库区某边坡的中风化砂岩为研究对象,分别对不同干湿循环次数作用下“干燥”和“饱和”状态的砂岩进行全断面CT扫描试验、巴西劈裂试验、单轴和三轴压缩试验。试验结果表明:在相同的干湿循环次数n下,“干燥”状态下砂岩的宏细观力学参数大于“饱和”状态下的参数;各典型区域的CT数均值随着循环次数非线性累积增加,初期变化较快,当n≥3时,细观损伤演化速度趋于缓慢;砂岩单轴抗压强度、弹性模量、抗拉强度、黏聚力、内摩擦角随n的增加呈对数下降,泊松比随n的增加而增大。干湿循环作用对砂岩不同力学参数的劣化程度不一,岩样“抵抗拉伸性能”大于“抵抗压缩性能”对水的敏感性。基于试验数据拟合,对不同干湿循环作用下两种含水状态的砂岩M–C屈服准则进行了修正,为工程中获得任意围压下岩石的破坏强度提供了理论依据。
Aiming at the problem of rock damage deterioration under the action of periodic wetting and drying cycles, taking the moderately weathered sandstone of a slope in the Three Gorges Reservoir Area as the research object, the effects of different wetting and drying cycles on “dry” and “saturated” Full-face CT scanning sandstone tests, Brazilian splitting tests, uniaxial and triaxial compression tests were performed. The experimental results show that under the same number of wet and dry cycles n, the macro and micro mechanical parameters of sandstone under “dry ” state are larger than those under “saturated ” state. The average CT value of each typical area varies with the number of cycles The non-linear cumulative increase, the initial change rapidly, when n ≥ 3, the evolution of mesoscopic damage tends to slow; uniaxial compressive strength of sandstone, elastic modulus, tensile strength, cohesion, internal friction angle with n Increasing logarithmically, Poisson’s ratio increases with increasing n. The effect of wetting and drying cycles on the mechanical properties of sandstone is different, and the sensitivity to water is higher than that of “tensile strength resistance” and “resistance to compressive strength”. Based on the experimental data fitting, the M-C yield criterion of two kinds of sandstone under different wetting and drying cycles is amended, which provides a theoretical basis for obtaining the rock failure strength under any confining pressure in the project.