回采巷道肩角泥岩片冒机理与防控

Mechanism and control of the rib spalling in mudstone in shoulder corner of underground mining roadway

针对回采巷道两侧肩角位置存在泥岩软弱夹层,易发生片帮冒落、出现“网兜”的问题,以冯家塔煤矿3205工作面运输平巷为工程背景,采用实验分析、数值模拟和现场监测相结合的方法,研究肩角泥岩吸水特性、片帮特征及其防控方法。结果表明:泥岩吸水具有时效特征,整个过程可分为加速吸水阶段和等速吸水阶段;泥岩片冒主要集中在巷道肩角和两底角位置,随着遇水弱化时间的增加,垂直应力最大值逐渐向肩角位置的深部转移;肩角泥岩片冒控制需要隔绝泥岩与水的接触,并控制泥岩膨胀变形和挤出;现场采用高强速凝水泥基材料喷涂巷道,隔离肩角泥岩与水接触,并控制泥岩膨胀变形,取得较好的控制效果,最大位移仅40 mm,且喷涂材料表面完整。

Aiming at the mudstone slab at shoulder corners on both sides of the mining roadway,which is prone to leading to rib spalling and the"tuck net".Taking the condition of mudstone slab in shoulder corners of transport roadway at the 3205 working face of Fengjiata Coal Mine as the engineering background,the water absorption characteristics,rib spalling characteristics,and prevention and control methods of mudstone slab in shoulder corner were studied using a combination of experimental analysis,numerical simulation and on-site monitoring.Results show that the procedure of mudstone water absorption has aging characteristics,and the whole process can be divided into the accelerated water absorption stage and the constant speed water absorption stage.Rib spalling is mainly reflected in the position of roadway shoulder corners and two bottom corners,and the maximum vertical stress gradually transfers to the depth of the shoulder corners with the increase of the weakening time.The core of control technique of the rib spalling in mudstone slab in roadway shoulder corners should be able to isolate mudstone from water,and control mudstone dilatancy and extrusion.Practice shows that by spraying large flow and ultra-early strength fast repair material,the deformation of surrounding rock monitored at each measuring point is small,the maximum displacement is only 40 mm,and the surface of spraying material is intact.