Experimental study on the development mechanism of coal bump considering the clamping effect of roof and floor

Besides the sufficient energy source for the development and occurrence of coal bump,the effective accumu-lation is also crucial. The constraint effect of roof and floor on coal seam was investigated through the clamping test. The results show that the displacements of the loading end and the central monitoring point are not synchronized,which proves the existence of atresia effect of rock specimen on coal specimen. The corresponding mechanism is capable of forming an effective energy accumulation. Meanwhile,the deformation conduction similar to P-wave was found at the local position of coal specimen,and the sudden adjustment of stress under a large axial pressure is a violent expression form of this feature. The research reveals that the atresia effect of roof and floor on coal seam and the deformation con-duction of itself have a promoting effect on coal bump. The field practice shows that the high pressure water injection with the surfactant through the position near to roof and floor can weaken the friction coefficient of interface efficiently, and reduce the bump hazard through the controllable release of the deformation energy deep in the coal seam.