微震监测揭示的C型采场空间结构及应力场

为研究开采强烈冲击倾向煤层解放层的卸压效果,采用微地震定位监测技术,对三面采空长壁工作面（解放层）的开采进行覆岩空间运动结构及应力场分布的监测。根据岩体在三维空间的破裂成像,揭示采场覆岩空间破裂与采动应力场的关系,得出以下结论：（1）工作面三侧采空区老顶上方的岩层形成C型空间结构,微震事件分布在C型结构的外侧,构成岩体破裂区,在C型结构的内侧为高应力区,并对高应力区域的转移及不同区域的应力状况进行了描述;（2）C型结构的最凹部在煤柱上方,煤柱最小时的支承压力分布为：在靠近上顺槽的区域,老顶以上的厚硬岩层已经发生断裂,形成卸压带;靠近下顺槽的区域,老顶以上的厚硬岩层未断裂,形成应力集中区。因此,通过监测确定被解放层的解放范围,对圈定的冲击危险区域预先采取防治措施,可实现安全开采。

C-SHAPED STRATA SPATIAL STRUCTURE AND STRESS FIELD IN LONGWALL FACE MONITORED BY MICROSEISMIC MONITORING

In order to study the results of relieving pressure above the seam which leads to rockburst while mining the liberation layer,China-Australia co-operation research group used microseismic monitoring techniques in Huafeng Mine of Xinwen Mining Group Co.,Ltd.,Shandong Province.The spatial fracturing rules of surrounding rock in longwall face surrounded by three sides mined areas were observed and researched.On the basis of the achievement of 3D strata fracturing situation and the section plane of microseimic events in different areas,the relationship between the spatial structure of overlying strata and mining pressure field is found,and the conclusions are drawn as follows:(1) the overlying strata forms C-shaped strata spatial structure.Microseimic events distribute in the outside of the C-shaped strata spatial structure and form fracture area of rockmasses.High stress area is in the C-shaped strata spatial structure.The shift of high stress area and the stresses of the different high stress areas are also described.(2) most concave of the C-shaped strata spatial structure lies on the top of the coal pillar when the coal pillar is smallest.The distribution of the supporting stress is that the hard thick rock layers above the main roof fracture near the intake airways,which produces the pressure-relieved area;and the hard thick rock layers above the main roof near the return airways are not fractured,which forms stress concentration area.According to the analysis of the reversal development of pressure,the diversion of high pressure is shown.The differences of pressure in different positions are found;and the areas where the pressure is not relieved are confirmed.So,by monitoring the area of the liberation layer and distinguishing the dangerous areas of rockburst,the measures to control rockburst are taken and succeeded.