Study of deformation-damage and acoustic emission character of coalrock under compression

Coalrock is a homogeneous medium. Under external loads, the microdefect nucleation, propagation and their interaction decide macroscopic deformation and damage character of coalrock. In order to study coalrock deformation and damage character under load and further reveal evolutionary process and the time effect mechanism of coalrock dynamic disaster, damage deformation and acoustic emission character of coalrock under compression was studied. A new damage variable which is defined based on normalized cumulative ring-down counts of acoustic emission is used to study deformation and damage character of coalrock. Damage evolution equation and damage constitutive model of coalrock under uniaxial compression are obtained. The results show that: acoustic emission of coalrock can demonstrate the deformation and damage evolution character; the new damage variable which is defined based on normalized cumulative ring-down counts of acoustic emission is reasonable; the deformation and damage evolution process can be divided into three departs including the stage of initial damage, the stage of damage stable evolution and development, the stage of damage accelerating development. The progress of coalrock deformation and damage can be regarded as a gradual development progress, which is the whole process from deformation and damage's initiation and evolution to the appearance of macroscopic cracks, from macroscopic propagation to damage.