Abstract: In the purpose of obtaining the deterioration of mechanical properties of sandstone under drying-wetting cycles, we conducted NMR and uniaxial compression tests on weakly cemented sandstones under different drying-wetting cycles, and monitored the damage process of sandstone under loading by using acoustic emission (AE) technology. By defining the porosity of sandstone as damage variable, we built damage deterioration model of rock under cyclic drying-wetting loading to explore the damage deterioration mechanism of loaded rock mass under drying-wetting. Our findings demonstrated that the increment of spectrum area of sandstone peaked at the beginning of cycle, and then attenuated with the proceeding of dry-wet cycles; the T2 spectral area of rock sample after uniaxial compression surged compared with that before failure. With the increase of cycle number, the plastic deformation of sandstone samples augmented, and the cumulative AE ring count reduced by 76.21% to the most. The uniaxial compressive strength and elastic modulus both decayed exponentially with the increase of drying-wetting cycles. By characterizing the deterioration of rock mechanical parameter with the deterioration degree, we found that the deterioration rate of uniaxial compressive strength decreased continuously with the increase of porosity.

Key words: rock mechanics, drying-wetting cycles, acoustic emission, nuclear magnetic resonance, degree of deterioration, damage evolution