冲刷带侵蚀工作面支架失稳机制及控制技术研究

Study on instability mechanism and control technology of support in erosion working face with erosion zone

保德煤矿8#煤层三盘区受冲刷带侵蚀影响,存在顶板大面积悬露问题,威胁工作面的生产安全。为解决81308工作面冲刷带侵蚀工作面矿压显著问题,保障冲刷带侵蚀区域煤层的安全高效开采,通过建立冲刷带侵蚀煤层采场覆岩结构模型,研究了顶板围岩失稳机制和支架承载特征,并提出了水力压裂顶板弱化措施。研究表明:在冲刷带侵蚀作用下顶板的来压步距有所增加;冲刷体破断垮落后对采空区的充填程度较高,使得关键层破断后回转下沉能够形成稳定的砌体梁结构,此时支架处于给定变形状态;来压期间支架所承受上覆岩层载荷略大于额定工作阻力,为避免压架事故发生,需采取水力压裂措施弱化顶板。支架载荷监测数据显示,通过水力压裂弱化顶板后,基本顶的初次来压步距为28 m,周期来压步距为20 m,来压较为平稳,仅小部分支架发生安全阀开启,表明顶板弱化措施取得了良好的成效。本文研究为保德煤矿及类似矿井提供指导和借鉴。

Affected by the erosion of scouring zone,the third panel of Baode Coal Mine 8#coal seam has a large area of roof hanging,which threatens the production safety of the working face.In order to solve the significant problem of ground pressure in the eroded working face in the scouring zone of 81308 working face and ensure the safe and efficient mining of coal seams in the eroded area of the scouring zone,by establishing the overburden structure model of the eroded coal seam stope in the scouring zone,the instability mechanism of roof surrounding rock and the bearing characteristics of support are studied,and the hydraulic fracturing roof weakening measures are put forward.The results show that the pressure step of roof increases under the erosion of scouring zone.After the scour body breaks and collapses,the filling degree of the goaf is high,so that the rotary subsidence of the key layer can form a stable masonry beam structure,and the support is in a given deformation state.During the pressure period,the overburden load borne by the support is slightly greater than the rated working resistance.In order to avoid the pressure accident,hydraulic fracturing measures should be taken to weaken the roof.The support load monitoring data show that after the roof is weakened by hydraulic fracturing,the initial pressure step of the basic roof is 28 m,the periodic pressure step is 20 m,and the pressure is relatively stable.Only a small number of supports have safety valves opened,indicating that the roof weakening measures have achieved good results.This study provides guidance and reference for Baode Coal Mine and similar mines.