Disaster-causing mechanism of compound dynamic disaster in deep mining under static and dynamic load conditions

In order to study the occurrence condition and behaviour characteristics of compound dynamic disaster of rock burst and coal-gas outburst under static and dynamic loading conditions,a series of true triaxial tests under differ- ent static stress combinations,alternating frequency and amplitude,strain-rate and gas pressure conditions of layered composite coal-rock were conducted by using the self-made “multi-functional true triaxial fluid-solid cou-pling experi- ment system”. The research results show that the intermediate principal stress,gas pressure,alternating frequency and amplitude and strain-rate have great influence on the behaviour of compound dynamic disaster. In general,the spalling failure is the main damage mode near the free face of layered composite coal-rock under true triaxial test conditions. Besides,the compound dynamic disaster can be divided into three types by load types:high static-load type,disturb- ance type and impact type,however,high pressure gas always plays a role of motive force and boosting power in either type of compound dynamic disaster,and both of its potential energy,seepage force and desorption expansion energy make positive contributions to the preparation and occurrence of compound dynamic disasters.