浅孔爆破切顶卸压在厚硬顶板沿空留巷中的应用研究

Study on the application of shallow hole blasting to roof cutting and pressure relief in gob side entry with thick and hard roof

针对厚硬顶板沿空留巷大面积悬顶、巷旁充填体大变形等问题,浅孔爆破切顶卸压是优化沿空留巷围岩结构的有效途径之一。以三河尖煤矿厚硬顶板为工程背景,采用LSDYNA数值模拟和理论计算方法分析了浅孔爆破切顶卸压机理,确定了合理的沿空留巷切顶卸压参数。研究结果表明:相邻炮孔可以起应力导向和叠加效应,裂隙产生以拉伸断裂破坏为主,破碎区和裂隙区为厚硬顶板断裂提供了弱面,厚硬顶板及时垮落,消除大面积顶板突然垮落产生急增压和冲击破坏的危险。采用浅孔爆破切顶卸压+巷旁充填体相结合的留巷围岩控制技术,建立了浅孔爆破切顶卸压沿空留巷力学模型,确定了炮孔深度为5000 mm、孔径为42 mm、装药不耦合系数为1.3、炮孔间距为900 mm、炮孔向采空区侧倾角为80°、充填体支护阻力为7.73 MN/m的切顶参数。研究成果成功应用于三河尖煤矿72207工作面沿空留巷切顶卸压工程实践,留巷围岩保持完整,维护效果较好。

Aiming at the problems of large-area overhanging roof and large deformation of the filling body,the use of shallow-hole blasting to cut the roof to relieve pressure is one of the effective way to optimize the surrounding rock structure of the gob-side entry retaining with thick and hard roof.Taking the thick and hard roof of Sanhejian Coal Mine as the engineering background,using LS-DYNA numerical simulation and theoretical calculation method,the mechanism of roof cutting and pressure relief by shallow hole blasting is analyzed,and the reasonable parameters of roof cutting and pressure relief along gob-side entry retaining are determined.The research results show that the blasting of adjacent blast holes can play a stress-oriented and superimposed effect,and the cracks are mainly caused by tensile fractures.The crushing area and the crack area provide a weak surface for the fracture of the thick and hard roof,and the thick and hard roof collapses in time,eliminating the danger of sudden pressure and impact damage caused by the sudden collapse of the large-area roof.Adopting the surrounding rock control technology of gob side entry retaining by shallow hole blasting combined with roof cutting and pressure relief and roadway side filling,the mechanical model of gob side entry retaining by shallow hole blasting is established,and the roof cutting parameters of 5000 mm hole depth,42 mm hole diameter,1.3 charge decoupling coefficient,900 mm hole spacing,80°hole to gob side angle and 7.73 MN/m filling support resistance are determined.The research results have been successfully applied to the roof cutting and pressure relief engineering practice of the gob side entry in 72207 working face of Sanhejian Coal Mine.The surrounding rock of the side entry remains intact and the maintenance effect is good.