采场顶板尖灭隐伏逆断层区导水裂隙发育特征

Development of Water Conductive Fissures in Hidden Reversed Fault in Thinning-out Overlying Strata of a Stope

为了防治采场项板尖灭的隐伏小断层(落差小于5 m)导致矿井突水,采用相似模拟试验,研究了工作面由下盘向上盘过顶板尖灭逆断层区域覆岩的渐进破断过程、采动应力和采动裂隙的演化特征.试验结果表明:当工作面未推进至断层面时,尖灭断层的上部裂隙张开,下部有闭合的趋势,且张开断层面的上部张开度大于下部;当工作面进入断层面时,下部顶板断层面张开;进入上盘岩层后,断层面逐渐闭合,且下部的闭合程度大于上部;下盘煤层支承压力的峰值系数显著增大,上盘煤岩层的支承压力峰值系数较小.下盘冒落充分,上盘则整体呈现悬臂梁弯曲下沉趋势;使得下盘导水裂隙高度大,上盘导水裂隙高度小.在断层尖灭点附近,导水裂隙在高度方向停止发展,完整岩层对构造导水裂隙竖向扩展有阻隔作用.

The aim of this paper is to prevent water from bursting induced by hidden reversed fault with a down throw less than 5 m in working stope. The dynamic fracture process of overlying strata, mining-induced stress and fissure of roof reversed fault in working face for advancing from lower plate to upper plate are simulated. The result shows that, when working face advances near to reversed fault, upper fissures of fault open, lower fissures tend to close, and the upper opening width of opening fault face is wider than that of the lower. Fault face of lower roof opens when working face advances into fault face. When working face advances into upper plate strata, fault face gradually close, with close degree of the lower being great than that of the upper. Peak coefficient of abutment pressure in lower plate coal seam will increase significantly, and that in the upper plate coal seam and strata is smaller. Lower plate roof has a full fall, but the upper plate roof wholly present the trend of cantilever beam bending subsidence, making the water conductive fissure height of lower plate become large and the upper plate become small. Water conductive fissures stop to further develop along height direction near the thinning-out area of the fault, so the complete strata have a barrier action to vertical development of structure fissure.