Abstract In order to solve the problem that the top-coal cannot be broken fully in mines under ground pressure causing the low recovery ratio of resources and violent strata behaviors in hard,thick and high-gas coal seam by fully mechanized top coal caving mining,the deep holes blasting forced roof caving was taken to pre-weaken the top-coal and gas drainage. The pre-weakening roof and pressure relief gas extraction mechanism was expounded by numerical simulation and theoretical analysis method. After dynamite blasting in hard top-coal,the surrounding coal of blasting holes produces a large number of fissures and significant displacement by explosion stress waves,stress was redistributed and thick top-coal was caved. At the same time,gas was desorbed and flowed along the fissure,the loose blasting crushing circle was formed around the hole and the efficiency of gas extraction was improved. Finally,the application of deep-hole blasting to pre-weakening roof and pressure relief gas extraction field test was taken in the 3801 working face of Shuiliandong coal mine. It is a good reference to high gas and hard top-coal caving working face in special thick seam mining under similar conditions.
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Received: 12 August 2013
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