深孔爆破在综放开采坚硬顶煤预先弱化和瓦斯抽采中的应用

APPLICATION OF DEEP BOREHOLE BLASTING TO TOP-COAL PRE-WEAKENING AND GAS EXTRACTION IN FULLY MECHANIZED CAVING

为解决坚硬特厚高瓦斯煤层采用综采放顶煤方法开采时,坚硬顶煤在矿山压力的作用下破坏不充分,从而造成煤炭资源的回采率低,同时使工作面呈现强烈的矿压显现和瓦斯浓度大而严重威胁工作面的安全等问题,提出深孔爆破顶煤预先弱化和瓦斯预抽技术。通过顺层钻孔煤层深孔爆破数值模拟和理论研究相结合的方法,揭示深孔爆破预裂顶煤和抽采卸压瓦斯机理。药柱在坚硬顶煤中爆破,爆破孔周边的煤体受爆轰应力波的作用产生裂隙并发生大幅度位移,使爆破孔周围的应力重新分布,厚层顶煤垮落;同时,在炮孔周围形成爆破松动破碎圈,瓦斯解吸沿着裂隙流动,提高瓦斯抽采效率。最后,在水帘洞煤矿3801工作面进行超前深孔爆破顶煤预先弱化和瓦斯抽采的现场应用,对类似条件下高瓦斯坚硬顶煤综放工作面特厚煤层开采具有很好的借鉴意义。

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.