关键词: 红层砂岩, 声波特性, 水-岩作用, 劣化机制

Abstract: Water-rock interaction is one of the most important causes of surface weathering, structure damage and strength reduction of rock. Water-rock interaction is also a classical problem of research field of rock and soil mechanics. In order to investigate the deterioration characteristics and mechanism of acoustic wave properties of red-bed sandstone in Lanzhou City, Gansu Province, a series of dry-wet cycle tests with different salt solutions is conducted. The research results show that the mass, P-wave and S-wave of red-bed sandstone specimens gradually decrease with the increasing of the number of dry-wet cycles with salt solution, especially with sulphate solution. Furthermore, it is easier for the samples perpendicular to the direction of bedding plane than the samples parallel to the direction of bedding plane to get deteriorated. Based on the P-wave spectrum analysis, the sulphate solution causes more energy loss than the sodium chloride solution. For the same salt solution, there is a highly positive correlation between the energy loss and the salt solution concentration. During the deterioration process, there are two types of deterioration, the end-face pulverization and rupture along the bedding plane. The microstructure analysis indicates that the cementation weakening of mineral particles and void increasing of rock due to the dry-wet cycles with salt solution are the main reasons of degradation of red-bed sandstone acoustic wave properties. Research results have important implications for the long-term slope stability evaluation of red-bed sandstone, and the evaluation and control of weathering disease of stone cultural heritage.

Key words: red-bed sandstone, acoustic wave properties, water-rock interaction, deterioration mechanism