Characteristics,types and prevention and control technology of rock burst in deep coal mining in China

In view of the large-scale deep mining of coal resources and the frequent occurrence of deep mining rock burst accidents in China,in order to clarify the characteristics of rock burst and its initiation types in deep mining and the difference of rock burst prevention measures between deep mining and shallow mining,and provide a theoretical and technical guidance for deep mining rock burst prevention and control,based on the research on the characteristics of deep mining rock burst in China,from the perspective of the load source of induced rock burst,and combining with the engineering examples,a mechanical model of rock burst in deep mining has been established,and three types of rock burst in deep mining in China have been put forward. Also,the dynamic and static load source control method of rock burst in deep mining roadway has been developed. The results show that the characteristics of rock burst in deep coal mining in China are as follows:due to the foundation static load is sufficient,the threshold of rock burst becomes lower,and the location of rock burst becomes widespread. Also,the occurrence percentages of rock burst with hidden principle,spontaneous and time-delay becomes high,the scope of prevention and control becomes expanded,the stress recovery becomes fast,and the requirements of high strength and long-term pressure relief becomes outstanding. The rock burst in deep coal mining in China is divided into three types,that is,deep dynamic static load superposition type,deep high static load loading type,and deep high static load unloading type. Because of the high pressure envi- ronment of deep coal resources,compared with the shallow part,the higher foundation static load can obtain the fretting load disturbance and their superimposition can produce a rock burst. The deep high static load loading can impact the ground pressure during the loading process at the limit equilibrium area and result in material instability,which leads to the dynamic instability of the engineering structure. While the deep high static load unloading can impact the ground pressure and reduce the minimum impedance band of high static load,and the static load unloading process is the re- sult of the destruction of the stability of surrounding rock structure,which leads to the dynamic instability of the engi- neering structure material. Therefore,there are essential differences between the two. Comparing with the prevention and control of conventional shallow buried impact ground pressure,the prevention and control of deep impact ground pressure shows that the foundation static load is sufficient,the dynamic load sources such as incremental roof are com- plex,and the threshold of acquiring incremental static load and dynamic load in the impact dangerous area is reduced. Therefore,the prevention and control of static and dynamic load sources must be realized with high intensity and long time,so as to prevent the formation of load inducing impact ground pressure conditions. Under the guidance of dynamic and static load separate source control concept,the roof “drill-cut-pressure” integration technology has been developed for roof dynamic load source to weaken the roof in depth and eliminate the roof dynamic load source. For the vertical stress concentration at the two sides of the roadway,the technology of 300 mm large diameter single hole drilling has been developed for the coal seam to mitigate the vertical stress of the coal body with high intensity and long time process. For the high horizontal stress at the bottom of roadway,the technology of installing pile foundation at the bottom corner of roadway has been developed,strongly cutting the horizontal stress and preventing the floor from impact and sliding. The mine applications of the technologies developed show an excellent effect.