松软顶板采场煤壁片帮与顶板冒落作用机理研究

Study on action mechanism of rib spalling and roof caving in mining stope under loose roof

以色连一号矿8101工作面为工程背景,通过现场实测松软顶板冒落形态和煤壁片帮形式,进行采场松软顶板冒落及煤壁片帮作用机理分析,采用数值模拟分析煤壁片帮前后松软顶板塑性区、应力及顶板下沉情况,提出了松软顶板冒落及煤壁片帮防治原则及措施。研究表明:1煤壁片帮导致工作面空顶距增大,加快松软顶板冒落;2理论分析结合现场实测得到工作面发生顶板冒落时0.5m≤[a]≤1.14m,工作面正常推进中(及时移架情况下)煤壁片帮后松软顶板极易冒落;3煤壁片帮后较片帮前来说,空顶区顶板出现拉伸破坏,支架上方顶板区域和煤体深部极限平衡区范围减小,片帮后顶板垂直应力增加明显,煤壁到支架间区域下沉量在0.5m,煤壁片帮导致空顶区顶板垂直应力、剪切应力和顶板下沉量都增大,顶板更容易发生冒落。

Based on engineering practice in 8101 working face of Selian No.1 coal mine,forms of loose roof caving and rib falling are obtained through the field observation,the roof caving and rib spalling mechanism is analyzed,and loose roof plastic zone,stress and roof convergence of coal wall,before and after rib spalling,are analyzed by numerical simulation,and the controlling principle and measures of loose roof caving and rib spalling are proposed.Several conclusions are obtained： Firstly,rib spalling leads to increase of empty-support distance in working face,increase of abutment pressure and the trend of extending to the deep of coal body,accelerate the caving of loose roof.Secondly,according to the theoretical analysis and field measurement,during roof caving in working face with 0.5m≤ [a] ≤1.14 m,when working face advances normally（with timely support advancing）,the loose roof falls easily after rib spalling.Lastly,after rib spalling,there is tensile failure of roof in empty-support distance,limit-equilibrium realm of coal body and roof above hydraulic support decreases,roof vertical stress increases significantly and roof subsidence is 0.5m between the supports to coal wall.The rib falling leads to increase of vertical stress,shear stress and roof convergence,which promotes the roof caving.