Cyclic dynamic-static loading and acoustic emission signal monitoring method of coal in solid–gas coupling environment and its application

The scientific essence of coal dynamic disaster is the damage and fracture dynamic effect under the superposition of dynamic and static loads. Obtaining the damage evolution law in the process of coal failure is the premise to explore its occurrence mechanism. One of the important indicators of coal damage is AE signals, but the accurate measurement of AE signals of coal under dynamic and static combined loading is a complex issue. Based on the triaxial test instrument, an integrated loading cylinder and dynamic sealing piston are developed to realize the accurate measurement of coal AE signal under dynamic and static combined loading and solid–gas coupling environment. Based on the above technique, the damage verification tests of coal under different cyclic dynamic load frequencies are carried out. The test results show that the dynamic-static combined loading technique created in this paper is reliable and the AE monitoring technique is feasible.