Analysis of Accumulated Damage Effects on the Roof of Mined-out Areas under Blasting Vibration

摘要

Under the repeated blasting vibrations, the roof of the mined-out areas will suddenly collapse and fall because of its accumulated damage, which is a hidden danger for the miners and equipment on the surface. Based on the mined-out areas in Antaibao Surface Mine, the three-dimension engineering geological model and computational model were built using FLAC~(3D) technique. According to the effect of the load of the mechanical construction equipment, and the blasting vibration velocity recorded by field monitoring, the equal-time-interval blasting vibration as normal incidence was exerted on the surface of the mined-out areas three times. Consequently the accumulated damage effect of the roof and surrounding rocks of mined-out areas were analyzed, the stress concentration extent and the range of principal stress were discussed as well. The dynamic response characteristics of deformation and the accumulated progressive displacement were revealed via the monitoring displacement curves. The above mentioned results can provide theoretical and technical basis for similar projects on reducing the hidden danger and ensuring safe mining.