After ore being mined,a great deal of elastic energy shall accumulate in the roof of the mined-out areas under high stress,and may suddenly release under certain conditions,cause impact hazard.A theoretical model for forecasting the maximum air speed of blast and destroy load occurring when roof of mined-out area collapses in large area was established,this can greatly simplify the theoretical analysis of impact hazard,and provide scientific and simple design basis for hazard prevention projects,is of great significance to the safety in mine production and hazard prevention.