Abstract:Based on numerical results of impacted roof movement at four stages which have been verified in-situ,the damping effects of roof movement at the impacted stage with three-dimensional distinct element code and chaotic dynamics theory are studied. With the increase of damping degree,the impact of roof movement decreases obviously and its damping inflection is at the point of 0.8. Meanwhile,the states of the system evolve from chaos to ordered steady state and then to chaos again. Index of chaotic degree shows that the system will develop towards the ordered and stable states with improvement of damping level,which can even change movement of impacted roof from initial active mode to passive mode. If the area of hanging impacted roof is large enough,measures to prevent rock burst may improve damping level of the system and change movement of the hard roof from impacted mode to periodic mode.