缓倾斜煤层孤岛工作面巷道底鼓机制及控制

针对缓倾斜煤层孤岛工作面回采巷道底鼓严重的状况,以庞庞塔矿5煤107工作面运输顺槽为研究背景,测试了顶底板的矿物成分、微观结构,利用物理模拟研究了底鼓机制,结果表明:①107工作面运输顺槽底板以高岭石为主,膨胀性岩石成分较低,岩石内部空隙较少,结构致密,强度高;②107工作面运输顺槽底鼓属于挤压流动性底鼓,掘进期间发生的是浅部岩层整体弯曲,在采动超前支承压力影响阶段,底板上位坚硬岩层超过其抗弯强度而发生破断,下位软弱底板解除约束,变形急剧增加,帮角出现裂隙,底板变形出现剧烈变形区、受限变形区、变形过渡区;③107工作面运输顺槽底鼓机制为:坚硬底板在高应力下的挤压流动是造成底鼓的主要原因,缓倾斜煤层巷道底板存在三角煤和底板岩石中存在少量膨胀性岩石对底鼓影响较小。针对性提出了采用开挖卸压槽释放压力方式进行底鼓治理,现场实测表明所提措施可有效降低巷道底鼓量。

Mechanism and Control Technology of the Gateway Floor Heave at Island Face of Gently Inclined Coal Seam

In view of the serious situation of the gateway floor heave on island face of gently inclined coal seam, the mineral composition and microstructure of the roof and floor slabs were tested on the background of the 107^th working face in Pangpangta Mine. The deformation mechanism of gateway floor was studied by physical simulation. The results show that: 1) The lithology of the headentry floor at the 107^th working face is mainly kaolinite, which has less expansive composition. The rock mass has fewer internal voids, dense structure and high strength; 2) The headentry floor heave of the 107^th working face, which occurs during the excavation and belongs to extrusion and fluidity type, is the overall bending of the shallow rock strata. At the stage when the advance bearing pressure is used for mining, the upper hard rock layer of the floor exceeds its flexural strength and breaks. Thus, the restraint on the lower soft floor is removed and deformation increases sharply. Cracks appear at the corner and severe deformation zone, limited deformation zone and deformation transition zone appear sequentially in the floor; 3) the mechanism of the headentry floor heave at 107 working face is as follows: extrusion flow of the hard floor under high stress is the main reason for the floor heave, while the existence of a small amount of expansive rock in the floor of the gently inclined coal seam has little effect on the formation of floor heave. Aiming at the specificity, the excavation pressure relief tank was adopted to release the pressure and mitigate the floor heave. On site measurement shows that the proposed measures can effectively reduce the degree of headentry floor heave.