The cyclic wetting-drying phenomenon is a complicated physical and chemical process. This kind of process will weaken the properties of rock to some extent. Some fundamental physical parameters of sandstone were first tested to study the weakening influence of wetting-drying cycles on the physical characteristics. Then, the water weakening effect on the mechanical and acoustic emission (AE) characteristics of rock on account of wetting-drying cycles was experimentally studied. Laboratory test results showed that when the number of cycles increased from 0 to 25, the density, P-wave velocity, uniaxial compressive strength (UCS), (elastic modulus (E)) and total AE counts of the rock specimens continuously decreased. However, the water absorption would increase as the number of cycles increased. The functional relationships between the total AE counts and the mechanical parameters (UCS and E) of sandstone after each cyclic number were established based on the test results. In addition, the chemical components and microstructure variations of rock undergoing wetting-drying cycles were examined. From the results, it can be concluded that microcrack growth and expansion inside the rocks undergoing wetting-drying cycles are the main reasons for the attenuation of the rock properties. Moreover, with increasing loading rate, the UCS, E and total AE counts of sandstone after each cyclic number would increase.

循环的干湿现象是一个复杂的物理和化学过程。这种过程会在某种程度上削弱岩石的性能。首先测试了砂岩的一些基本物理参数，以研究干湿循环对物理特性的弱化影响。然后，通过湿-干循环实验研究了水减弱对岩石的机械和声发射（AE）特性的影响。实验室测试结果表明，当循环次数从0增加到25时，岩石样本的密度，P波速度，单轴抗压强度（UCS），（弹性模量（E））和总AE计数均不断降低。但是，吸水率将随着循环次数的增加而增加。根据测试结果确定每个循环数后的砂岩E）。此外，检查了岩石经历干湿循环的化学成分和微观结构变化。从结果可以得出结论，经历干湿循环的岩石内部微裂纹的生长和膨胀是破坏岩石性能的主要原因。此外，随着加载速率的增加，每个循环数后砂岩的UCS，E和总AE计数将增加。