Study on Gas Drainage Hole and whole of Coal Sample Acoustic Emission Failure Law under Complex Stress

Experiments on gas drainage drilling and whole of coal sample were carried out by the electrohydraulic servo of rock triaxial test systems and the acoustic emission (AE) system. The test results indicate that coal sample including gas drainage borehole is first the borehole unstability which leads to the whole instability, complete coal sample suddenly destroys multiple blocks. Gas drainage borehole coal sample damage duration shorter, but it appears many times. Complete coal sample happens to some serious damage that duration will reach to maximum. Complete coal sample appear AE count blank area early than gas drainage borehole coal sample. Coal sample including gas drainage borehole releases more energy than complete coal sample. Complete coal sample takes place low frequency when stresses do not change, at other times, whatever stress rising or falling peak frequency hold on around 300 KHz. coal sample including gas drainage borehole first falls existing loading blank area and damage which happens before low frequency gap area.