不稳定覆岩下沿空掘巷围岩大变形机理

Large Deformation Mechanism of Roadway Driving Along Goaf Under Unstable Overlying Rock Strata

为了掌握不稳定覆岩下沿空掘巷围岩大变形的机理,采用矿用钻孔窥视仪对不稳定覆岩下的沿空掘巷顶板岩层进行了钻孔摄像观测,提出了"基本测量尺度-裂隙条数法"钻孔裂隙统计方法,采用该方法对沿空掘巷顶板岩层中的裂隙进行了统计分析,并研究了裂隙分布及其演化规律。研究表明:纵向裂隙和横向裂隙为不稳定覆岩下沿空掘巷顶板岩层中2种基本的裂隙形式,其中纵向裂隙多分布于巷道上部顶板岩层中,而横向裂隙多出现在靠近采空区煤壁的顶板下部岩层中;随着上区段采空区上覆岩层稳定时间的延长,纵向裂隙逐渐演化成断裂带,横向裂隙逐渐演化成离层和径向错位,2种裂隙相互交叉延展极易形成异常破碎带;不稳定覆岩下沿空掘巷围岩大变形的根本原因是基本顶的断裂、回转和滑移,控制该类巷道围岩大变形的基本思路就是控制基本顶断裂后的关键块的回转和滑移。

In order to grasp the large deformation mechanism of roadway driving along goal under un- stable overlying rock strata, the digital panoramic borehole camera system was adopted to observe the roof rock strata of the roadway driving along goal. Count Fracture Numbers in a Basic Measuring Scale Method was proposed to undertake borehole fracture statistical analysis. According to the method, the fractures in the roof of the roadway driving along goaf were statistically analyzed; fractures distribution as Well as the evolution law was also investigated. Observation results indicate that longitudinal frac- tures and transverse fractures are two major fracture forms in roof rock strata. As for the distribution, the longitudinal fractures are mainly found on the top of the roof strata in the roadway, while the transverse fractures distribute in the bottom of the roof strata along goaf. As the stabilization time of the overlying strata of the goaf went by, the longitudinal fractures gradually evolved into fracture zone, and the trans-verse fractures evolved into roof separation zone and radial dislocation. When the two forms of fracture cross together, a wide range of abnormal fracture zone would come into being very easily. The field ob-servation confirms that the primary causes of the overlying strata deformation of the roadway driving along goaf are the fracture of the main roof, the rotating of the key block and its sinking and slippage. Therefore, in order to control the rotating and slippage of the key block after the fracture of the main roof will be a fundamental method to control the deformation of the roadway driving along goaf.