采空区侧向悬臂切顶破断长度研究及应用

Research and application of breaking length of lateral cantilever roof cutting in goaf

巷道煤柱侧采空区(侧向顶板)经常会遇到厚硬顶板,短期内不会自然垮落,容易诱发矿震及垮顶等事故。以泊江海子矿113105工作面为研究背景,针对侧向长悬臂造成的强矿压现象,基于顶板断裂力学,建立采空区侧向长悬臂力学模型,对切顶前后顶板间岩体断裂长度进行分析。结果表明:岩体的抗拉强度、厚度和摩擦系数较大时,断裂后的前梁长度较长;当岩体的密度及切顶角度增大时,断裂后的后梁长度较长;通过物理试验,切顶后长悬臂断裂成2块5~8 m长的块体,顶板呈周期垮落特性,实现了对巷道侧向悬臂岩层的主动卸压目的。现场试验表明:爆破切顶后围岩应力得到转移,矿压显现减少,巷道变形能满足工作面正常回采需求,保障了矿井的高产高效。

The goaf at the side of the roadway pillar(lateral roof)often encounters thick and hard roof,which will not collapse naturally in a short period of time,and is easy to cause mine earthquake and roof fall.Taking the 113105 working face of Bojiang Haizi Coal Mine as the research background,aiming at the strong ground pressure phenomenon caused by the lateral long cantilever,based on roof fracture mechanics,a mechanical model of lateral long cantilever of goaf is established to analyze the fracture length of rock mass between the roof before and after roof cutting.The results show that when the tensile strength,thickness and friction coefficient of rock mass are large,the front beam length after fracture is longer;when the unit weight and cutting angle of rock mass increase,the back beam length after fracture is longer.Through physical test,the long cantilever broke into two 5-8 m long blocks after roof cutting,and the roof collapsed periodically,realizing the purpose of active pressure relief on the lateral cantilever rock layer of the roadway.The field test shows that the surrounding rock stress is transferred after the blasting roof cutting,the ground pressure manifestation is reduced,and the roadway deformation can meet the normal mining demand of the working face,ensuring the high production and high efficiency of the mine.