Mechanism of repeated rock bursts in extra-thick coal seam

Taking the rock burst recurring in the same region as the engineering background, the mechanism of the repeated rock bursts is explored by using the methods of theoretical analysis, field monitoring and numerical simulation. The results are as follows: (1) The region with repeated rock bursts in extra-thick coal seam has stress restoration phenomenon, and the extra-thick coal seam expands under source of force is the major reason which leads to stress restoration; (2) The repeated impact is the result of competition of many times between the impact force and the impedance force of the impacted body, and rock burst occurs many times during coal body transfers from relatively complete state to fracturing state when the impact force is greater than impedance force, till the coal body fractures completely. (3) Eliminating the force and stopping stress restoration can prevent the recurrence of rock burst. The results of this study may provide a useful reference for the prevention and control of rock bursts in extra-thick coal seam.