超长孤岛工作面沿空掘巷矿压显现规律及原因分析

Reasons Analysis and Pressure Law of Gob-side Entry Driving of Extra Long Isolated Working Face

为研究孤岛工作面条件下矿压显现规律及巷道支护,以两淮矿区刘庄矿120502超长孤岛工作面机巷为工程背景,通过现场实测以及FLAC^(3D)数值模拟软件对该孤岛工作面沿空掘巷矿压显现规律进行研究。结果表明:巷道顶板离层量较大,离层量最大达到117mm,且以浅部离层为主;在巷道掘进前期巷道围岩变形较小,随后巷道围岩变形随距巷道起点距离增加而增大,在距巷道起点600～800m之间变形更为剧烈,120503工作面采空区侧变形最大,平均值为180. 41mm,最大值为780mm,依次为煤体实侧(平均值为138. 23mm,最大值为445mm)、底鼓(平均值为124. 29mm,最大值为545mm)、顶板下沉(平均值为64. 03mm,最大值为430mm);由于垂直应力在煤柱内形成弹性核,使垂直应力达到32. 5MPa,工作面侧垂直应力达到26. 3MPa,相比增加了6. 2MPa,机巷邻近采空区侧受120502工作面开采影响大,使采空区变形增大;由于巷道采用直墙三心拱断面,顶部拱结构将垂直应力转换为切向应力,塑性区显示顶板受压底板受拉,由于岩石具有抗压不抗拉特性,因此顶板下沉小于底鼓量,并针对性地提出了巷道加强支护技术。工程实践表明,在初始支护设计的基础上,通过锚网索与喷浆、注浆联合等加强支护手段可以有效地对巷道围岩变形进行控制。

In order to study mine pressure behavior and roadway supporting of isolated working face,it taking transportation roadway of 120502 extra long isolated working face of Lianghuai mine district as engineering background,and then mine pressure law of gob-side entry driving of the isolated working face was studied by field test and FLAC 3D number simulation software.The results showed that roadway roof separation amount was large,and the largest separation amount was about 117mm,and most separation was shallow separation,roadway surrounding rock deformation was small during earlier period of roadway driving,and then roadway deformation increased with distance increased,deformation was fiercely as distance to roadway start point was 600~800m,deformation was the largest at gob side of 120503 working face,it’s average value was 180.41mm,the largest value was 780mm,successively were coal body side(an average was 138.23mm,the largest was 445mm),floor heave(an average was 124.29mm,the largest was 545mm),roof subsidence(an average value was 64.03mm,the largest was 430mm),elastic core formed within coal pillar as vertical stress,and vertical stress reached about 32.5MPa,vertical stress at working face side arrived 26.3MPa,it’s value increased about 6.2MPa,god side of transportation roadway deformation largely as 120502 working face mining,also gob area deformation increased,straight wall and three centers arch section was applied during roadway tunneled,vertical stress was converted to tangential stress,plastic zones showed that compressed stress appeared around roof but tension stress appeared at floor,as better characteristics of compress resistance,so roof subsidence less than floor heave,specific roadway enhancement supporting technology was put forward.The practical showed that based on original supporting design,roadway surrounding rock deformation could be effectively controlled by some combination supporting means of anchoring net cable,guniting and grouting and so on.