Deformation and acoustic emission characteristics of dry and saturated rock fractures

The natural rock masses are situated in various complex geological conditions. Quantitative description of the deformation and failure behaviors of rock fractures under these conditions is of fundamental importance for the studies related to their mechanical behaviors. In this study, the unconfined compression tests and the elastic-plastic contact numerical simulations are implemented to study the compressive deformation and failure behavior of two kinds of rock fractures under dry and saturated conditions, together with acoustic emission detection and analysis. The results show that the normal stress-displacement curves and the plastic failure areas obtained from the experiment and the numerical simulation agree well with each other, which verifies the reliability of the contact method. The mean increment of plastic deformation decreases nonlinearly with the increasing normal stress with a decreasing rate, and a fitting formula is established using mechanical and geometric parameters. The position of acoustic emission (AE) sources matches with the damage area obtained from the experiment and the numerical simulation. Both the AE ringing count and the cumulative count are higher in dry rocks than those in saturated rocks. The AE ringing count and the mean increment of plastic deformation follow an identical changing trend. These results reveal the controlling role played by the fundamental mechanical parameters and geometric properties in the deformation and failure behaviors of rock fractures.