摘要
高应力是深部矿井冲击地压灾变频率走高的主要原因,充填开采则是控制岩层运动,缓解采动应力集中程度,降低围岩破坏和冲击风险的有效手段。为研究采空区充填体对超前采动应力的控制能力,以山东古城煤矿1123充填工作面为工程背景,采用理论分析、室内试验、现场实测手段探究充填开采工作面采动应力分布规律,揭示超前采动应力对充填体充实率的反馈机制,指导冲击地压矿井充实率确定。结果表明:工作面开采初期充填体充实率低于80%,坚硬顶板下沉量大,超前采动影响范围大于30 m,应力集中系数达到1.5,断层影响区采动应力影响范围和集中系数分别增至60 m和1.65,片帮冒顶等围岩失稳现象增多;实测了采空区充填体承载应力全程动态演化特征,承载应力分布曲线划分为“快速降低—短暂稳定—快速升高—缓慢降低—二次稳定”5个阶段,低充实率条件下采空区上、中、下3个区域承载应力稳定值分别为1.9、5.2、2.8 MPa;将采空区充填体划分为非充分压实区和充分压实区,构建了充填体支撑作用下坚硬顶板连续沉降模型,得到了坚硬顶板“ʅ”型沉降曲线,非充分压实区范围随充实率近似呈线性减小;试验得到充填体弹性模量和单轴抗压强度随凝固时间的演化曲线,结合顶板沉降曲线和推进速度得到工作面前后采动应力全区域分布曲线;建立了超前采动应力集中程度与充填体承载能力的负指数函数关系,揭示了超前采动应力对充填体充实率的负向反馈机制,实现充填开采降载防冲效果的定量评价;提出了充填体充实率“三位一体”协同提升措施,将1123工作面充实率升高至90%,增强了充填体承载能力,超前采动应力集中系数降至1.3,厚顶煤膨胀变形量减少至50 mm,坚硬顶板破断致冲风险显著降低。
High stress is the main reason for high frequency of rock burst in deep coal mines.Backfilling mining serves as an effective method to control roof strata movement,alleviate the degree of stress concentration,and reduce the failure of surrounding rock and the risk of rock burst.To evaluate the controlling ability of the backfilling on mining stress in the gob area,the 1123 longwall panel of the Gucheng mine is taken as the project background.Theoretical analysis,laborat-ory test and field measurement are used to study the mining-induced stress distribution in the backfilling longwall face,and to reveal the feedback mechanism between the front abutment stress and bearing capacity of the backfilling body,helping to determine the backfilling rate of coal burst mine.The results show that the backfilling ratio in the early stage is lower than 80%,the subsidence of hard roof is serious,the influence area of front abutment stress is more than 30 m,and the degree of stress concentration reaches 1.5.The influence area and concentration degree of mining-induced stress in the fault affected area increase to 60 m and 1.65,respectively.Surrounding rock instability phenomenon,such as rib spalling and roof fall,happens frequently.The whole dynamic evolution characteristics of bearing stress in the backfilling body is measured.The stress distribution curve is divided into five stages,namely rapid decrease,transient stabilization,rapid in-crease,slow decrease,and secondary stabilization.The stabilization values of the bearing stress in the upper,middle,and lower regions of the gob area under the condition of low backfilling ratio are 1.5,5.2 and 2.5 MPa,respectively.The back-filling body in the gob area is divided into non-sufficiently compacted zones and sufficiently compacted zones,and the continuous subsidence model of the hard roof under the support of the backfilling body is constructed,and the“ʅ”type subsidence curve of the hard roof is obtained,and the range of the insufficiently compacted area decreases approximately linearly with the backfilling ratio.The test obtains the evolution curves of elastic modulus and uniaxial compressive strength of the back-filling body with time.By combining with the roof subsidence curve and face advance speed,the dis-tribution curve of mining-induced stress in the whole area of the longwall face is obtained.Negative exponential relation-ship is established for the backfilling rate and the afront abutment stress,which reveals the reverse feedback mechanism between them.Quantitative assessment on the load reduction and burst prevention effect of backfilling mining is realized.The trinity enhancement measures for improving the backfilling ratio of the gob area are proposed,which raises the back-filling ratio of the 1123 working face to more than 90%.The bearing capacity of the backfilling body is strengthened.The trinity measures reduce the separation space under the hard roof to 50 mm.The stress concentration coefficient decreases to 1.3.Correspondingly,the controlling effect of the surrounding rock of the longwall panel is significantly improved.
作者
王兆会
陈明振
李强
王伟
李增强
徐德生
郑晓晨
孙少龙
吴传平
郭心洋
安君琦
WANG Zhaohui;CHEN Mingzhen;LI Qiang;WANG Wei;LI Zengqiang;XU Desheng;ZHENG Xiaochen;SUN Shaolong;WU Chuanping;GUO Xinyang;AN Junqi(School of Energy and Mining Engineering,China University of Mining and Technology-Beijing,Beijing 100083,China;Jining Energy Bureau,Jining 272000,China;Shandong Coal Science and Technology Research Institute Branch,Yankuang Energy Group Co.,Ltd.,Jinan 250117,China;Shandong Dongshan Gucheng Coal Mine Co.,Ltd.,Jining272000,China;Wutongzhuang Coal Mine,Jizhong Energy Fengfeng Group Co.,Ltd.,Handan056011,China)
出处
《煤炭学报》
EI
CAS
CSCD
北大核心
2024年第4期1804-1818,共15页
Journal of China Coal Society
基金
国家自然科学基金资助项目(51934008)
中央高校基本科研业务费资助项目(2023ZKPYNY01)。
关键词
冲击地压
充填开采
坚硬顶板
采动应力
反馈机制
rock burst
backfilling mining
hard roof
mining-induced stress
feedback mechanism
