切顶爆破卸压技术研究

Research on Pressure Relief Technology of Cutting Top Blasting

针对某煤矿1208采区沿空留巷存在顶板压力大、矿压显现强烈、巷道变形大等问题,分析了1208工作面推进时顶板破断特征,确定切顶爆破的关键参数;1208工作面进行爆破切顶卸压后,可使初次来压步距减少13.9 m,动载系数下降0.5,同时,顶煤的大面积垮落也减少了28 m,使初次来压、初次放煤时间变短,来压强度减小,防止大范围悬顶垮塌的发生,避免支柱在大面积悬顶垮落时的冲倒风险。对钻孔的考察,在爆破切顶后8 m左右的范围内,钻孔的孔壁上有明显的裂缝;这些裂缝是由工作面的采动所致,彼此贯通。采空区内的顶煤悬挂在这些贯通的裂隙中,并随断层一起垮落,从而提高了煤层的回收率。

Aiming at the problems of high roof pressure,strong mining pressure manifestation,and large roadway deformation in 1208 mining area of a coal mine along the hollow stay lane,the characteristics of roof fracture during the advancement of the 1208 working face were analyzed,and the key parameters of roof cutting blasting were determined;After blasting and cutting the roof to relieve pressure in the 1208 working face,the initial pressure step distance can be reduced by 13.9 m,the dynamic load coefficient can be reduced by 0.5,and at the same time the large-scale collapse of the top coal can be reduced by 28 m.This shortens the time for the initial pressure and coal release,reduces the strength of the pressure,prevents the occurrence of large-scale collapse of the suspended roof,and avoids the risk of pillar collapse during large-scale collapse of the suspended roof.During the investigation of drilling,within the range of about 8 meters after the top cutting of the blasting,there were obvious cracks on the borehole wall;These cracks are caused by mining on the working face and are interconnected with each other.The top coal in the goaf is suspended in these interconnected cracks and collapses along with the faults,thereby improving the recovery rate of the coal seam.