Effect of water on mechanical behavior and acoustic emission response of sandstone during loading process: phenomenon and mechanism

In this paper, a series of uniaxial compression experiments were carried out on sandstone with varying water contents, and acoustic emission (AE) signals were synchronously collected in the experimental process. It reveals that water content has a significant effect on the mechanical behavior and AE signals of sandstone. As the water content increases, both the uniaxial compression strength and the elastic modulus decrease while the peak strain and energy dissipation increase. In the perspective of AE signals, both the peak and the cumulative AE energy drop with the water content, and an exponential empirical function was proposed to describe their relationships. Multi-fractal analyses of AE signals were also performed. The uniformity of signal distribution (∆a) and the difference between frequencies of largest and smallest signals (∆f) also decrease with the increase of water content. All these phenomena can be explained by the fact that more and more intergranular fractures occur at the higher water content condition. Moreover, a sudden increase of ∆a and a sudden decrease of ∆f in time series can be used as the precursor of rock destabilization and failure which have potential engineering application value. •Water reduces the strength of sandstone, increases energy dissipation and weakens acoustic emission(AE).•The change of micro fracture mechanism of sandstone is an important reason.•The multifractal parameters ∆a and ∆f of AE have potential engineering application value.