A new burst evaluation index of coal–rock combination specimen considering rebound and damage effects of rock

摘要

Obtaining the bursting liability is essential for rock burst mitigation. To reasonably evaluate the bursting liability of coal in deep coal mining, a new modified bursting energy index considering rebound and damage effects of rock is proposed. Then, uniaxial compressive tests of gypsum–rock combination specimens with different rock types are conducted for researching the energy evolution and bursting liability. Third, the traditional bursting energy index KsubE/sub and modified bursting energy index KsubED/sub are compared. At last, the reasonability of KsubED/sub is verified through PFC2D simulation. Results show: (1) When evaluating the bursting liability of coal–rock combination, the rebound and damage effects of rock must be considered. (2) The uniaxial compressive strength of gypsum–rock combination specimen nonlinearly increases with increasing rock strength, but the dynamic failure duration exponentially decreases. (3) KsubE/sub and KsubED/sub all increase linearly when the rock strength increases. (4) The slope of fitting curve of KsubED/sub is smaller than that of KsubE/sub, indicating that the bursting liability calculated by KsubE/sub is strengthened. (5) PFC2D simulation shows that KsubED/sub decreases with increasing number of drilling hole in the coal component. When using KsubED/sub to evaluate the bursting liability of coal–rock combination, it is more reasonable and applicable.