Relationship between the acoustic characteristics and damage variable in the process of uniaxial loading and unloading

Underground excavation is an unloading process, which not only results in the change of stress distribution in surrounding rocks, but also gives rise to the change in rock properties. In order to analyze the stability of slope and optimize the design, studies on the change in mechanical properties of rocks, due to unloading process caused by excavation in an open-pit mine, must be carried out. In uniaxial loading and unloading process, the damage process in rocks was tested by ultrasonic wave and acoustic emission, in which the damage development was dynamically measured by acoustic emission and the damage degree was quantitatively estimated based on ultrasonic wave. The result shows that new damage can be induced in both loading and unloading processes. The damage development and its evolution process can be dynamically measured by monitoring of acoustic emission, and the level of damage evolution can be quantitatively estimated by the signal characteristics of ultrasonic wave.