As a typical form of weathering, cyclic wetting-drying treatment on host rock is commonly encountered in many applications of geotechnical engineering. How cyclic wetting-drying weathering affects the strength and deformation behavior of host rock is a topic worthy of comprehensively investigating. In this study, the influence of cyclic wetting-drying weathering on mechanical behavior of a medium-grained sandstone is experimentally investigated. The sandstone specimens are first subjected to different wetting-drying weathering cycles, and uniaxial compression tests and direct shear tests are then conducted on these prepared specimens. The results show that the water absorption of the rock monotonically increases with the increase of the number of wetting-drying cycle in the treatment. The strength and deformation properties (i.e., uniaxial compressive strength, Young's modulus, cohesion, and friction angle) are found to decrease with the increase of wetting-drying cycle in the treatment and the decrease gradually diminishes as the number of wetting-drying cycle becomes large. Upon failure of the rock specimen under both uniaxial compression and direct shear, the integrity is progressively weakened and more fragments can be observed as the number of wetting-drying cycle in the treatment gradually increases. The deterioration of rock strength and deformation properties is found to be mainly associated with the micro-cracks generated inside the rock in response to cyclic wetting-drying weathering. The data in this study provide useful guidance for long-term stability evaluation of engineering structures constructed under cyclic wetting-drying weathering condition.

作为一种典型的风化形式，在岩土工程的许多应用中经常会遇到对主岩进行循环干湿处理。干湿循环风化对母岩强度和变形行为的影响是一个值得综合研究的课题。本研究通过实验研究了干湿循环风化作用对中粒砂岩力学行为的影响。砂岩试件首先经受不同的干湿风化循环，然后对这些制备的试件进行单轴压缩试验和直剪试验。结果表明，随着处理中干湿循环次数的增加，岩石的吸水率单调增加。强度和变形特性（即 单轴抗压强度、杨氏模量、内聚力和摩擦角）随着处理中干湿循环的增加而降低，并且随着干湿循环次数的增加而逐渐减小。岩石试样在单轴压缩和直接剪切下破坏后，完整性逐渐减弱，随着处理中干湿循环次数的逐渐增加，可以观察到更多的碎片。发现岩石强度和变形特性的恶化主要与岩石内部响应干湿风化作用而产生的微裂纹有关。本研究数据为干湿循环风化条件下建造的工程结构的长期稳定性评价提供了有益的指导。