Classification of rock burst in coal mine based on energy storage and release bodies

The research system of rock burst includes occurrence mechanism,occurrence criterion and prediction and prevention based on mechanism and criterion. As a result of many and various types of factors affecting rock burst,the traditional research mostly focuses on the research of mechanism,monitoring and prevention inde-pendently,which re- sults in blindness in the prediction and prevention of rock burst in the field. In order to master rock burst systematically and improve the efficiency of prediction and prevention of rock burst,the existing classification methods of rock burst were investigated and a new classification method of rock burst based on energy storage and energy release bodies was put forward. The mechanism of rock burst in various types was analyzed based on the disturbance response insta- bility theory of rock burst. The mechanical models of rock burst in various types were established,and the correspond- ing analytical solutions and the estimating formulas of the energy re-leased during the occurrence were obtained. The application of classification method in prediction and prevention was also discussed. The results show that rock burst can be divided into three types according to different energy storage and release bodies:coal type,roof type,fault zone and surrounding rock type. For coal type,the rock burst is resulted from the storage and release of elastic energy of compressed coal mass,and the occurrence conditions are determined by uniaxial compressive strength σc and impact tendency index K. The release energy is inversely proportional to impact tendency index K. For roof type,the rock burst is resulted from the fracture instability of roof in roof-coal seam deformation system. The larger the tensile strength σt of roof,the larger the critical goaf span Lcr of rock burst occurrence,and the larger the energy released during instability and collapse. For fault zone and surrounding rock type,the rock burst is resulted from fault zone rock instability during softening stage in fault zone and surrounding rock system. The instability condition is determined by the fault structure and shear modulus of surrounding rock. The energy released during instability is proportional to the fault drop. Based on the comprehensive analysis of various types of rock burst,for coal type,roof type and fault zone and surrounding rock type,the methods of monitoring of critical stress Pcr ,deformation monitoring of roof and stress monitoring near faults were put forward to monitor occurrence of rock burst,respectively. Methods of control of critical stress Pcr ,sup- port or induced breakage of roof,reducing stress concentration at fault were put forward to prevent and control rock burst,respectively.