急斜煤层顶板应力叠加效应致灾特征综合分析

摘要

针对乌鲁木齐矿区急斜煤层粉砂岩顶板可能面临的突然性断裂垮落所引发的动力灾害问题,采用现场调研、理论分析、数值计算和联合分析方法,综合分析综放短壁工作面顶板集中应力叠加效应诱致动力灾害特征.根据煤岩层赋存条件和开采布局,考虑采场裂隙分布规律和开采扰动影响,采用分区组合方法构建三维有限差分数值计算模型.计算结果表明:①43号和45号煤层顶板均以其深部区域岩体为“支点”产生倾向和走向撬压效应,两者在空间上的叠加效应加剧了局部岩体的应力集中程度,使顶板岩层破断呈现“破断—平衡—破断”周期规律性;②两煤层顶板集中应力分别位于其相应工作面南巷南帮的左下方和左上方,距南帮中点20.5和13.7m;③顶板应力集中区走向长度分别为68.2和61.5m,集中应力峰值分别位于工作面前方28.5和25.3 m,顶板对巷帮应力集中影响系数分别为0.52和0.81.基于研究成果制定了“注水-爆破”耦合致裂顶板防控措施,动力灾害得到有效控制,这为急斜煤层开采顶板动力灾害防控提供借鉴.%Aiming at the threat of dynamic hazards encountered by roof in Urmchi mine district,a numerical model was established by three dimensional explicit finite-difference program (FLAC3D) with regional combination method based on mining layout and lithological characteristics.Meanwhile,the distribution characteristics of surrounding rock fracture and influence of mining disturbance were taken into consideration.And some relevant results indicated that the strike and dip pry-press function was generated with the deep coal-rock mass of No.43 and No.45 coal seam as supporting point.In addition,the superimposed effect of functions exacerbated the degree of roof stress.Also,the positions of roof stress of No.43 and No.45 were located,the bottom left and bottom right of corresponding working face separately,20.5 m and 13.5 m away from corresponding south roadway respectively.Furthermore,the strike length of roof concentrated stress area was 68.2 m and 61.5 m,and peak concentrated stress was located 28.5 m and 25.3 m before working face separately.Stress monitoring result showed that the concentrated stress of south roadway of No.43 and No.45 coal seam had a nonlinear variation tendency with roof concentrated stress,and the influence coefficient was 0.52 and 0.81 respectively.Therefore,roof concentrated stress can be calculated with influence coefficient,which is able to assess and predict the possibility and risk level of roof dynamic hazards.Prevention and control measures have been taken based on the research result and dynamic hazards have been controlled effectively,which has certain actual engineering significance.