Damage evolution and acoustic emission characteristics of hydrochemically corroded limestone

To explore the deterioration characteristics and damage principle of mechanical properties of limestone under the coupling action of aqueous chemical solution and consecutive loading-unloading cycles, the mechanics of limestone under different chemical corrosion conditions was studied by laboratory cyclic consecutive loading-unloading test combined with acoustic emission monitoring. The results show that the peak strain and peak strength of limestone exhibit more significant deterioration with lower pH acid and longer corrosion time. The main failure mode of limestone does not change; however, the through-cracks become larger with lower pH acid and longer corrosion time; the quality and longitudinal wave velocity of limestone corroded by aqueous chemical solution exhibit obvious deterioration characteristics, especially in a solution at pH = 2; limestone reacts with aqueous chemical solution, in which the amount of H⁺ ions determines the degree of corrosion, which indicates the deterioration of mechanical characteristics of limestone macroscopically; the pH value of aqueous chemical solution has a significant effect on the acoustic emission signal. In the later stage of loading and unloading, a significant Felicity effect appears in limestone, and FR is negatively correlated with cycle number and corrosion time and positively correlated with pH value; the cumulative ring count damage factor D is used to reveal the evolution of damage to the limestone specimens. The results can provide experimental reference for evaluating long-term stability of engineering rock mass under the coupling action of hydrochemical solution and consecutive loading-unloading cycles.