中文摘要：

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。

英文摘要：

The intermediary weathered sandstone of a slope in the Three Gorges Reservoir area is taken as the research object when investigating the damage and degradation of rock under periodic wetting-drying cycles. The full section CT scan, Brazil disk split tests and uniaxial compression tests on sandstones under different wetting-drying cycle times （n） are performed respectively. The results show that the macro mesoscopic mechanical parameters of dry sandstone are greater than those of wet sandstone under the same wetting-drying cycle times. The mean values of CT numbers in typical areas nonlinearly and cumulatively increase with the increase of wetting-drying cycle times. They change faster initially, and the mesoscopic damage evolution rate tends to slow down when the wetting-drying cycle times exceed three. The uniaxial compressive strength, elasticity modulus, tensile strength, cohesion and internal friction angle of sandstone decrease logarithmically with the increase of wetting-drying cycle times, while the Poisson＇s ratio of sandstone increases as the wetting-drying cycle times increase. The role of wetting-drying circulation on deterioration degree of different mechanical parameters of sandstone is variant. The sensibility of tensile properties of sandstone specimen to water is greater than that of compression properties of sandstone one. The M-C yield criterion of sandstone under dry and wet conditions is corrected respectively based on the data regression analysis, thus providing a theoretical basis for the breaking strength acquisition of rock under arbitrary confining pressure.