巨厚弱胶结覆岩深部开采大能量事件与地表沉陷关系研究

Study on the relationship between large energy events and surface subsidence in deep mining of super-thick weakly cemented overburden

陕蒙矿区是我国重要的煤矿开采基地,区域侏罗系煤层覆岩中普遍存在巨厚弱胶结覆岩,虽然覆岩岩性总体呈中硬偏软弱,但实测地表下沉相对较小,且伴随频繁的大能量事件发生,给工作面安全高效开采带来了较大安全隐患。为研究巨厚弱胶结覆岩深部开采大能量事件与地表沉陷的关系,对石拉乌素煤矿1203工作面与1208工作面进行了地表沉陷实测与矿震资料分析,获得了该地区地表移动变形规律和矿震数据,通过对比分析研究发现:巨厚弱胶结覆岩地表移动变形下沉分布集中,最大下沉处均位于工作面中部偏向已采工作面侧,整体地表下沉盆地形态及下沉增加过程与中东部相似,但在未达到充分采动时,西部巨厚弱胶结矿区地表下沉值相比中东部明显偏小;巨厚弱胶结矿区煤层回采过程中均存在微震事件的活跃期,该阶段微震事件的能量和次数较高,同时伴随着105 J≤E的大能量事件发生,105 J≤E的矿震事件虽然频次较低,但在能量释放上占据重要地位;弱胶结矿区地表沉陷与能量事件之间存在着关联性,随着工作面的推进,最大下沉值突变往往伴随着大能量事件的发生。

Shaanxi-Mongolia mining area is an important coal mining base in China.The Jurassic coal seam overburden in the region generally has super-thick weakly cemented overburden.Although the overburden lithology is generally medium hard to weak,the measured surface subsidence is relatively small,and frequent large energy events occur,which brings great potential safety hazards for safe and efficient mining of the working face.In order to study the relationship between large energy events and surface subsidence in deep mining of super-thick weakly cemented overburden,the surface subsidence measurement and mine earthquake data analysis are conducted on the 1203 working face and 1208 working face of Shilawusu Coal Mine,and the surface movement and deformation rules and mine earthquake data of the area are obtained.Through comparative analysis,it is found that the surface movement and deformation subsidence of super-thick weakly cemented overburden is concentrated,and the maximum subsidence is located in the middle of the working face to the side of the mined working face.The overall surface subsidence basin shape and subsidence increase process are similar to those in the central and eastern parts of China.However,when the mining is not fully developed,the surface subsidence value of the western super-thick weakly cemented mining area is significantly smaller than that of the central and eastern parts.There is an active period of microseismic events in the mining process of coal seam of super-thick weakly cemented mining area.The energy and frequency of microseismic events in this stage are relatively high,and they are accompanied by large energy events with 105 J≤E.Although the frequency of mine earthquake events with 105 J≤E is low,they play an important role in energy release.There is a correlation between surface subsidence and energy events in weakly cemented mining areas.With the advance of working face,the maximum subsidence value mutation is often accompanied by the occurrence of large energy events.