超千米深部矿井采动应力显现规律
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摘要
我国浅部煤炭资源逐渐耗竭,开采深度逐渐进入1 000～2 000 m水平,常常伴有大量的工程灾害,其根本原因是深部采动应力场的显现规律与响应规律不清楚。以平煤股份十二矿超千米深己15-31030工作面为研究基地,开展了不同开采速率下超千米煤层采动应力显现规律及响应特征研究,并集成"锚杆应力-钻孔应力-钻孔裂隙窥视"等研究手段进行现场原位测试。结果表明:随着采煤工作面的不断推进,超前支承压力峰值先是交替上升,回采距离超过80 m时,由于埋深较大导致支承压力峰值增长变缓并最终在85 MPa左右波动,应力集中系数达3. 3,高于一般浅部工作面集中系数;同时上覆岩层在采动影响下形成垮落带、断裂带、弯曲下沉带的"三带"结构;其次,随着开采速度增大,超前支承压力峰值逐渐增大,峰值点距采煤工作面的距离相应减小,基本顶断裂形成的岩块长度也越长;工作面支架压力随着采煤工作面持续推进呈现出周期上升的趋势。在采动影响下,由于扰动后应力重分布及能量释放,锚杆应力呈现出先增长后降低的趋势,得出工作面采动影响范围大约为85 m,钻孔应力距采煤工作面75 m左右时进入采动影响范围开始上升,而后进入支承压力降低区,应力开始出现小幅度下降;随着采煤工作面不断推进,强烈的开采扰动导致裂隙不断发育,裂隙逐渐发育成纵横交错的破碎带,并向顶板上方发展。
In China,the shallow mineral resources of the earth have been gradually exhausted. There are lots of engineering disasters in deep mining when mining at 1 000-2 000 m depths due to the unknown mechanism in deep mining-induced stress field. At the Ji15-31030 mining face with an over-kilometer depth in Pingdingshan Coal Mine No.12,the research was carried out to study the mining-induced stress evolution law with different mining speeds. The insitu monitoring tests including bolt stress testing,borehole stress testing and fractures in borehole monitoring were also carried out to investigate the appearance law of mining-induced stress field. Results showed that the peak advanced abutment pressure increases alternately as the mining face advances and fluctuates around 85 MPa due to great depths when mining over 80 m. The stress concentration factor is 3.3,which is higher than that at shallow mining face. Overlying strata forms "three-zones" consisting of the caving zone,cracked zone and bent zone. Meanwhile,the peak advanced abutment pressure increases as the mining speed increases gradually,and the distance between peak pressure position and mining face decreases correspondingly,and the longer the length of the rock formed by the main roof breaking is. Hydraulic support pressure increases periodically with mining face advances. The bolt stress increases first and then decreases due to stress redistribution and energy releasing under the influence of mining,which concludes that mining influenced range is about 85 m. Borehole stress increases in the mining influence range about 75 m from the mining face,and decreases slightly when entering the advanced abutment pressure reduction zone. Strong mining disturbance results in fractures developing continuously as mining face advances,and fractures develop into crisscross broken zone as developed upwards.
In China,the shallow mineral resources of the earth have been gradually exhausted. There are lots of engineering disasters in deep mining when mining at 1 000-2 000 m depths due to the unknown mechanism in deep mining-induced stress field. At the Ji15-31030 mining face with an over-kilometer depth in Pingdingshan Coal Mine No.12,the research was carried out to study the mining-induced stress evolution law with different mining speeds. The insitu monitoring tests including bolt stress testing,borehole stress testing and fractures in borehole monitoring were also carried out to investigate the appearance law of mining-induced stress field. Results showed that the peak advanced abutment pressure increases alternately as the mining face advances and fluctuates around 85 MPa due to great depths when mining over 80 m. The stress concentration factor is 3.3,which is higher than that at shallow mining face. Overlying strata forms "three-zones" consisting of the caving zone,cracked zone and bent zone. Meanwhile,the peak advanced abutment pressure increases as the mining speed increases gradually,and the distance between peak pressure position and mining face decreases correspondingly,and the longer the length of the rock formed by the main roof breaking is. Hydraulic support pressure increases periodically with mining face advances. The bolt stress increases first and then decreases due to stress redistribution and energy releasing under the influence of mining,which concludes that mining influenced range is about 85 m. Borehole stress increases in the mining influence range about 75 m from the mining face,and decreases slightly when entering the advanced abutment pressure reduction zone. Strong mining disturbance results in fractures developing continuously as mining face advances,and fractures develop into crisscross broken zone as developed upwards.
引文
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[17]李智,王汉鹏,李术才,等.煤层开采过程中上覆岩层裂隙演化规律研究[J].山东大学学报(工学版),2011,41(3):142-147.LI Zhi,WANG Hanpeng,LI Shucai,et al.Study on the fissure evolution law of overlying strata during mining[J].Journal of Shandong University(Engineering Science),2011,41(3):142-147.
[18]潘俊锋,齐庆新,毛德兵,等.冲击性顶板运动及其应力演化特征的3DEC模拟研究[J].岩石力学与工程学报,2007,26(S1):3546-3552.PAN Junfeng,QI Qingxin,MAO Debing,et al.Study on movement and stress evolutionary process of impacted roof with 3DEC[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(S1):3546-3552.
[19]CUNDALL P.A computer model for simulating progressive large scale movement in block rock systems[A].Proceedings of the Symposium of the International Society for Rock Mechanics[C].France:International Society for Rock Mechanics(ISRM),1971:129-136.
[20]王泳嘉,刘国兴,邢纪波.离散元法在崩落法放矿中应用的研究[J].有色金属工程,1987(2):22-28.WANG Yongjia,LIU Guoxing,XING Jibo.Research on applications of discrete element method in ore drawing for caving system[J].Nonferrous Metals,1987(2):22-28.
[2]谢和平,高峰,鞠杨,等.深部开采的定量界定与分析[J].煤炭学报,2015,40(1):1-10.XIE Heping,GAO Feng,JU Yang,et al.Quantitative definition and investigation of deep mining[J].Journal of China Coal Society,2015,40(1):1-10.
[3]谢和平.“深部岩体力学与开采理论”研究构想与预期成果展望[J].工程科学与技术,2017(2):1-16.XIE Heping.Research framework and anticipated results of deep rock mechanics and mining theory[J].Advanced Engineering Sciences,2017(2):1-16.
[4]谢和平,周宏伟,薛东杰,等.煤炭深部开采与极限开采深度的研究与思考[J].煤炭学报,2012,37(4):535-542.XIE Heping,ZHOU Hongwei,XUE Dongjie,et al.Research and consideration on deep coal mining and critical mining depth[J].Journal of China Coal Society,2012,37(4):535-542.
[5]谢和平,周宏伟,刘建锋,等.不同开采条件下采动力学行为研究[J].煤炭学报,2011,36(7):1067-1074.XIE Heping,ZHOU Hongwei,LIU Jianfeng,et al.Mining-induced mechanical behavior in coal seams under different mining layouts[J].Journal of China Coal Society,2011,36(7):1067-1074.
[6]YAVUZ H.An estimation method for cover pressure re-establishment distance and pressure distribution in the goaf of longwall coal mines[J].International Journal of Rock Mechanics&Mining Sciences,2004,41(2):193-205.
[7]LUXBACHER Kray,WESTMAN Erik,SWANSON Peter,et al.Three-dimensional time-lapse velocity tomography of an underground longwall panel[J].International Journal of Rock Mechanics&Mining Sciences,2008,45(4):478-485.
[8]ISLAM Md Rafiqul,SHINJO Ryuichi.Numerical simulation of str-ess distributions and displacements around an entry roadway with igneous intrusion and potential sources of seam gas emission of the Barapukuria coal mine,NW Bangladesh[J].International Journal of Coal Geology,2009,78(4):249-262.
[9]ISLAM Md Rafiqul,HAYASHI Daigoro,KAMRUZZAMAN A B M.Finite element modeling of stress distributions and problems for multi-slice longwall mining in Bangladesh,with special reference to the Barapukuria coal mine[J].International Journal of Coal Geology,2009,78(2):91-109.
[10]SHABANIMASHCOOL,MAHDI,LI C C,et al.A numerical study of stress changes in barrier pillars and a border area in a longwall coal mine[J].International Journal of Coal Geology,2013,106:39-47.
[11]YANG Wei,LIN Baiquan,YAN Qing,et al.Stress redistribution of longwall mining stope and gas control of multi-layer coal seams[J].International Journal of Rock Mechanics&Mining Sciences,2014,72:8-15.
[12]XIE Jing,GAO Mingzhong,ZHANG Ru,et al.Lessons learnt from measurements of vertical pressure at a top coal mining face at datong tashan mines,China[J].Rock Mechanics and Rock Engineering,2016,49(7):2977-2983.
[13]谢和平,于广明,杨伦,等.采动岩体分形裂隙网络研究[J].岩石力学与工程学报,1999,18(2):147-151.XIE Heping,YU Guangming,YANG Lun,et al.Research on the fractal effects of cracknetwork in overburden rock stratum[J].Chinese Journal of Rock Mechanics&Engineering,1999,18(2):147-151.
[14]ZHOU Hongwei,ZHANG Tao,XUE Dongjie,et al.Evolution of mining-crack network in overburden strata of longwall face[J].Journal of China Coal Society,2012,36(12):1957-1962.
[15]GAO Mingzhong,JIN Wencheng,DAI Zhixu,et al.Relevance between abutment pressure and fractal dimension of crack network induced by mining[J].International Journal of Mining Science and Technology,2013,23(6):925-930.
[16]GAO Mingzhong,ZHANG Ru,XIE Jing,et al.Field experiments on fracture evolution and correlations between connectivity and abutment pressure under top coal caving conditions[J].International Journal of Rock Mechanics and Mining Science,2018(111):84-93.
[17]李智,王汉鹏,李术才,等.煤层开采过程中上覆岩层裂隙演化规律研究[J].山东大学学报(工学版),2011,41(3):142-147.LI Zhi,WANG Hanpeng,LI Shucai,et al.Study on the fissure evolution law of overlying strata during mining[J].Journal of Shandong University(Engineering Science),2011,41(3):142-147.
[18]潘俊锋,齐庆新,毛德兵,等.冲击性顶板运动及其应力演化特征的3DEC模拟研究[J].岩石力学与工程学报,2007,26(S1):3546-3552.PAN Junfeng,QI Qingxin,MAO Debing,et al.Study on movement and stress evolutionary process of impacted roof with 3DEC[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(S1):3546-3552.
[19]CUNDALL P.A computer model for simulating progressive large scale movement in block rock systems[A].Proceedings of the Symposium of the International Society for Rock Mechanics[C].France:International Society for Rock Mechanics(ISRM),1971:129-136.
[20]王泳嘉,刘国兴,邢纪波.离散元法在崩落法放矿中应用的研究[J].有色金属工程,1987(2):22-28.WANG Yongjia,LIU Guoxing,XING Jibo.Research on applications of discrete element method in ore drawing for caving system[J].Nonferrous Metals,1987(2):22-28.