深部煤岩体卸荷损伤变形演化特征数值模拟及验证
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摘要
为研究保护层开采过程中下伏煤岩体卸荷损伤变形演化特征,运用FLAC~(3D)数值模拟方法及现场实验测量手段,以山西保德煤矿实际情况为研究背景,对保护层开采过程中下伏煤岩体应力、变形、塑性演化规律进行了研究及验证。研究表明:保护层开采过程中,被保护层应力呈增大—减小—增大的变化规律,下伏煤岩体应力在空间上呈现出明显的"O"形应力分布规律;受保护层采动影响,下伏煤层测点经过原岩应力、应力集中、采动卸压、应力恢复4个阶段;最大应力集中系数与最小卸荷比为固定值,且出现时间相同,工作面前方应力集中系数与工作面后方卸荷比均呈往复性变化,变化周期与工作面来压周期相关;本文实例中,最大应力集中系数约为1. 32,此时测点受到的z向应力值达到最大;最小卸压比约为4. 4%,此时测点受到的z向应力值达到最小,卸压效果最好;受应力变化影响,被保护层呈压缩—恢复—膨胀—回缩的基本变化规律,最终状态保持一定的膨胀变形,与应力分区相对应,根据不同变形特征可将下伏煤层分为原岩状态区、压缩变形区、卸压膨胀区、变形恢复区;本文实例中11号煤层最大膨胀变形量约为0. 6%,此时测点裂隙最为发育,增透效果最好,有利于瓦斯卸压抽采;受应力变化影响,下伏煤岩体塑形区域范围在空间上呈先xyz三向增大—x轴方向单向增大y轴z轴2个方向稳定的变化规律;随着工作面的回采,被保护层煤体塑性区范围在x轴方向不断增加;通过实测保德煤矿81307工作面回采过程中下伏11号煤地应力、膨胀变形量,对深部煤岩体卸荷损伤变形演化特征数值模拟结果进行了验证,下伏11号煤地应力、膨胀变形量变化规律与数值模拟规律较为吻合。
To study the evolution characteristics of unloading damage and deformation of underlying coal and rock during the protective layer mining period,FLAC~(3D) numerical simulation was conducted based on the actual conditions of Baode Coal Mine in Shanxi Province,China. In-situ investigations were also adopted to verify the simulation results on stress,deformation and plastic property evolution laws. The results show that the stress of the protected layer increases firstly,then decreases and after which increases again during the mining process. The spatial distribution of stress on underlying coal and rock shows an obvious "O" shape. Influenced by the protective layer mining,the measurement points in underlying coal seam experienced four stages including original rock stress,stress concentration,mining pressure relief and stress recovery. The ratio of the maximum stress concentration factor and the minimum unloading stress is a constant value,and the occurrence of the two extreme values shares the same time. The stress concentration factor in front of the working face and the unloading ratio behind the working face all change reciprocally,and the change period is related to the cycle stress from the working face. In this paper,the maximum stress concentration factor is about1.32,at which time the value of thez-direction stress at the measuring point is the largest. The minimum pressure relief ratio is about 4.4% and thez-direction stress value at the measuring point is the smallest at this time and the pressure relief effect is also the best. Under the effects of changing stress,the deformation of the protected layer presents the basic rule of compres-sion-recovery-expansion-retraction cycle. The final state maintains a certain expansion deformation,which corre-sponds to the stress zoning. According to the different deformation characteristics,the underlying coal seam can be divided into original rock state zone,compression deformation zone,pressure relief expansion zone and de-formation recovery zone. The example in this paper shows that the maximum expansion deformation of No.11 coal seam was 0.6%. The cracks at the monitoring points developed well and the permeability increased significantly,which was conducive to gas pressure relief and extraction. Under the influence of stress changes,the plastic area increased in triaxial directions first,then increased inx-axis direction buty-axis andz-axis direction kept stable. With the advance of working face,the plastic zone of coal body in protected seam increased continuously in thex-axis direction. By measuring the in-situ stress and expansion deformation of No.11 coal in the mining process of 81307 working face in Baode Coal Mine,the numerical simulation results of the evolution characteristics of unloading damage and deformation during deep mining were verified. The variation laws of in-situ stress and expansion deformation of No.11 coal agree well with those of numerical simulation.
To study the evolution characteristics of unloading damage and deformation of underlying coal and rock during the protective layer mining period,FLAC~(3D) numerical simulation was conducted based on the actual conditions of Baode Coal Mine in Shanxi Province,China. In-situ investigations were also adopted to verify the simulation results on stress,deformation and plastic property evolution laws. The results show that the stress of the protected layer increases firstly,then decreases and after which increases again during the mining process. The spatial distribution of stress on underlying coal and rock shows an obvious "O" shape. Influenced by the protective layer mining,the measurement points in underlying coal seam experienced four stages including original rock stress,stress concentration,mining pressure relief and stress recovery. The ratio of the maximum stress concentration factor and the minimum unloading stress is a constant value,and the occurrence of the two extreme values shares the same time. The stress concentration factor in front of the working face and the unloading ratio behind the working face all change reciprocally,and the change period is related to the cycle stress from the working face. In this paper,the maximum stress concentration factor is about1.32,at which time the value of thez-direction stress at the measuring point is the largest. The minimum pressure relief ratio is about 4.4% and thez-direction stress value at the measuring point is the smallest at this time and the pressure relief effect is also the best. Under the effects of changing stress,the deformation of the protected layer presents the basic rule of compres-sion-recovery-expansion-retraction cycle. The final state maintains a certain expansion deformation,which corre-sponds to the stress zoning. According to the different deformation characteristics,the underlying coal seam can be divided into original rock state zone,compression deformation zone,pressure relief expansion zone and de-formation recovery zone. The example in this paper shows that the maximum expansion deformation of No.11 coal seam was 0.6%. The cracks at the monitoring points developed well and the permeability increased significantly,which was conducive to gas pressure relief and extraction. Under the influence of stress changes,the plastic area increased in triaxial directions first,then increased inx-axis direction buty-axis andz-axis direction kept stable. With the advance of working face,the plastic zone of coal body in protected seam increased continuously in thex-axis direction. By measuring the in-situ stress and expansion deformation of No.11 coal in the mining process of 81307 working face in Baode Coal Mine,the numerical simulation results of the evolution characteristics of unloading damage and deformation during deep mining were verified. The variation laws of in-situ stress and expansion deformation of No.11 coal agree well with those of numerical simulation.
引文
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[4]YUAN Liang.Theory and practice of integrated coal production and gas extraction[J].International Journal of Coal Science&Technology,2015,2(1):3-11.
[5]袁亮.卸压开采抽采瓦斯理论及煤与瓦斯共采技术体系[J].煤炭学报,2009,34(1):1-8.YUAN Liang.Theory of pressure relieved gas extraction and technique system of integrated coal production and gas extraction[J].Journal of China Coal Society,2009,34(1):1-8.
[6]AQ1050-2009,保护层开采技术规范[S].北京:煤炭工业出版社,2009.
[7]汪有刚,李宏艳,齐庆新,等.采动煤层渗透率演化与卸压瓦斯抽放技术[J].煤炭学报,2010,35(3):406-410.WANG Yougang,LI Hongyan,QI Qingxin,et al.The evolution of permeability and gas extraction technology in mining coal seam[J].Journal of China Coal Society.2010,35(3):406-410.
[8]张村,屠世浩,袁永,等.卸压开采地面钻井抽采的数值模拟研究[J].煤炭学报,2015,40(S2):392-400.ZHANG Cun,TU Shihao,YUAN Yong.Numerical simulation of surface gas venthole extraction in pressure relief mining[J].Journal of China Coal Society.2015,40(S2):392-400.
[9]AGUADO M B D,NICIEZA C G.Control and prevention of gas outbursts in coal mines,Riosa-Olloniego coalfield,Spain[J].International Journal of Coal Geology,2007,69(4):253-266.
[10]CUI X,BUSTIN R M.Volumetric strain associated with methane desorption and its impact on coalbed gas production from deep coal seams[J].AAPG Bulletin,2005,89(9):1181-1202.
[11]程远平,刘洪永,郭品坤,等.深部含瓦斯煤体渗透率演化及卸荷增透理论模型[J].煤炭学报,2014,39(8):1650-1658.CHENG Yuanping,LIU Hongyong,GUO Pinkun,et al.A theoretical model and evolution characteristic of mining-enhanced permeability in deeper gassy coal seam[J].Journal of China Coal Society,2014,39(8):1650-1658.
[12]CHENG Yuanping,WANG Liang,LIU Hongyong,et al.Definition,theory,methods,and applications of the safe and efficient simultaneous extraction of coal and gas[J].International Journal of Coal Science&Technology,2015,2(1):52-65.
[13]程志恒,齐庆新,李宏艳,等.近距离煤层群叠加开采采动应力-裂隙动态演化特征实验研究[J].煤炭学报,2016,41(2):367-375.CHENG Zhiheng,QI Qingxin,LI Hongyan,et al.Evolution of the superimposed mining induced stress-fissure field under extracting of close distance coal seam group[J].Journal of China Coal Society,2016,41(2):367-375.
[14]谢和平,张泽天,高峰,等.不同开采方式下煤岩应力场-裂隙场-渗流场行为研究[J].煤炭学报,2016,41(10):2405-2417.XIE Heping,ZHANG Zetian,GAO Feng,et al.Stress-fracture-seepage field behavior of coal under different mining layouts[J].Journal of China Coal Society,2016,41(10):2405-2417.
[15]SI G,SHI J Q,DURUCAN S,et al.Monitoring and modelling of gas dynamics in multi-level longwall top coal caving of ultrathick coal seams,Part II:Numerical modelling[J].International Journal of Coal Geology,2015,144-145:58-70.
[16]许家林,钱鸣高.覆岩采动裂隙分布特征的研究[J].矿山压力与顶板管理,1997(3,4):210-212.XU Jialin,QIAN Minggao.The study of the distribution characteristics of mining-induced fracture in overlying rock strata[J].Ground Pressure and Strata Control,1997(3,4):210-212.
[17]许家林.岩层采动裂隙分布在绿色开采中的应用[J].中国矿业大学学报,2004,33(2):141-144.XU Jialin.Study and application of mining-induced fracture distribution in green mining[J].Journal of China University of Mining&Technology,2004,33(2):141-144.
[18]周世宁.煤层瓦斯赋存与流动理论[M].北京:煤炭工业出版社,1999.
[19]刘天泉.矿山岩体采动影响与控制工程学及其应用[J].煤炭学报,1995,20(1):1-5.LIU Tianquan.Influence of mining activities on mine rock mass and control engineering[J].Journal of China Coal Society,1995,20(1):1-5
[20]白矛,ELSWORTH D,刘天泉.采动引起的岩体变形及地下水流动的数值分析-稳定流研究[J].煤炭学报,1998,23(6):289-294.BAI Mao,ELSWORTH D,LIU Tianquan.Nnmerical analysis of rock deformation and flow of underground water caused by coal extraction-stable flow[J].Journal of China Coal Society,1998,23(6):289-294.
[21]于不凡.开采解放层的认识与实践[M].北京:煤炭工业出版社,1986.
[22]张勇,许力峰,刘珂铭,等.采动煤岩体瓦斯通道形成机制及演化规律[J].煤炭学报,2012,37(9):1444-1450.ZHANG Yong,XU Lifeng,LIU Keming,et al.Formation mechanism and evolution laws of gas flow channel in mining coal and rock[J].Journal of China Coal Society,2012,37(9):1444-1450.
[23]王家臣,邵太升,赵洪宝,等.上保护层开采卸压释放作用数值模拟研究[A].和谐地球上的水工岩石力学-第三届全国水工岩石力学学术会议论文集[C].2010:182-186.
[24]翟成.近距离煤层群采动裂隙场与瓦斯流动场耦合规律及防治技术研究[D].徐州:中国矿业大学,2008:48-50.ZHAI Cheng.Research on coupling laws between facture field and gas flow field of short-distance coal seam group and preventive technology[D].Xuzhou:China University of Mining and Technology,2008:48-50.
[25]钱鸣高,许家林.覆岩采动裂隙分布的“O”形圈特征研究[J].煤炭学报,1998,23(5):20-23.QIAN Minggao,XU Jialin.Study on the“O-shape”circle distribution characteristics of mining induced fractures in the overlaying strata[J].Journal of China Coal Society,1998,23(5):466-469.
[26]王露,许家林,吴仁伦.采动煤层瓦斯充分卸压应力判别指标理论研究[J].煤炭科学技术,2012,40(3):1-5.WANG Lu,XU Jialin,WU Renlun.Theoretical study on stress distinguishing index of gas pressure fully released in mining seam[J].Coal Science and Technology,2012,40(3):1-5.
[27]中国矿业大学.长钻孔深部基点法测试装置[P].中国专利:CN201220233853.6,2012-12-26.
[2]何满潮,谢和平,彭苏萍,等.深部开采岩体力学研究[J].岩石力学与工程学报,2005,24(16):2803-2813.HE Manchao,XIE Heping,PENG Suping,et al.Study on rock mechanics in deep mining engineering[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(16):2803-2813.
[3]俞启香.矿井瓦斯防治[M].徐州:中国矿业大学出版社,1992.
[4]YUAN Liang.Theory and practice of integrated coal production and gas extraction[J].International Journal of Coal Science&Technology,2015,2(1):3-11.
[5]袁亮.卸压开采抽采瓦斯理论及煤与瓦斯共采技术体系[J].煤炭学报,2009,34(1):1-8.YUAN Liang.Theory of pressure relieved gas extraction and technique system of integrated coal production and gas extraction[J].Journal of China Coal Society,2009,34(1):1-8.
[6]AQ1050-2009,保护层开采技术规范[S].北京:煤炭工业出版社,2009.
[7]汪有刚,李宏艳,齐庆新,等.采动煤层渗透率演化与卸压瓦斯抽放技术[J].煤炭学报,2010,35(3):406-410.WANG Yougang,LI Hongyan,QI Qingxin,et al.The evolution of permeability and gas extraction technology in mining coal seam[J].Journal of China Coal Society.2010,35(3):406-410.
[8]张村,屠世浩,袁永,等.卸压开采地面钻井抽采的数值模拟研究[J].煤炭学报,2015,40(S2):392-400.ZHANG Cun,TU Shihao,YUAN Yong.Numerical simulation of surface gas venthole extraction in pressure relief mining[J].Journal of China Coal Society.2015,40(S2):392-400.
[9]AGUADO M B D,NICIEZA C G.Control and prevention of gas outbursts in coal mines,Riosa-Olloniego coalfield,Spain[J].International Journal of Coal Geology,2007,69(4):253-266.
[10]CUI X,BUSTIN R M.Volumetric strain associated with methane desorption and its impact on coalbed gas production from deep coal seams[J].AAPG Bulletin,2005,89(9):1181-1202.
[11]程远平,刘洪永,郭品坤,等.深部含瓦斯煤体渗透率演化及卸荷增透理论模型[J].煤炭学报,2014,39(8):1650-1658.CHENG Yuanping,LIU Hongyong,GUO Pinkun,et al.A theoretical model and evolution characteristic of mining-enhanced permeability in deeper gassy coal seam[J].Journal of China Coal Society,2014,39(8):1650-1658.
[12]CHENG Yuanping,WANG Liang,LIU Hongyong,et al.Definition,theory,methods,and applications of the safe and efficient simultaneous extraction of coal and gas[J].International Journal of Coal Science&Technology,2015,2(1):52-65.
[13]程志恒,齐庆新,李宏艳,等.近距离煤层群叠加开采采动应力-裂隙动态演化特征实验研究[J].煤炭学报,2016,41(2):367-375.CHENG Zhiheng,QI Qingxin,LI Hongyan,et al.Evolution of the superimposed mining induced stress-fissure field under extracting of close distance coal seam group[J].Journal of China Coal Society,2016,41(2):367-375.
[14]谢和平,张泽天,高峰,等.不同开采方式下煤岩应力场-裂隙场-渗流场行为研究[J].煤炭学报,2016,41(10):2405-2417.XIE Heping,ZHANG Zetian,GAO Feng,et al.Stress-fracture-seepage field behavior of coal under different mining layouts[J].Journal of China Coal Society,2016,41(10):2405-2417.
[15]SI G,SHI J Q,DURUCAN S,et al.Monitoring and modelling of gas dynamics in multi-level longwall top coal caving of ultrathick coal seams,Part II:Numerical modelling[J].International Journal of Coal Geology,2015,144-145:58-70.
[16]许家林,钱鸣高.覆岩采动裂隙分布特征的研究[J].矿山压力与顶板管理,1997(3,4):210-212.XU Jialin,QIAN Minggao.The study of the distribution characteristics of mining-induced fracture in overlying rock strata[J].Ground Pressure and Strata Control,1997(3,4):210-212.
[17]许家林.岩层采动裂隙分布在绿色开采中的应用[J].中国矿业大学学报,2004,33(2):141-144.XU Jialin.Study and application of mining-induced fracture distribution in green mining[J].Journal of China University of Mining&Technology,2004,33(2):141-144.
[18]周世宁.煤层瓦斯赋存与流动理论[M].北京:煤炭工业出版社,1999.
[19]刘天泉.矿山岩体采动影响与控制工程学及其应用[J].煤炭学报,1995,20(1):1-5.LIU Tianquan.Influence of mining activities on mine rock mass and control engineering[J].Journal of China Coal Society,1995,20(1):1-5
[20]白矛,ELSWORTH D,刘天泉.采动引起的岩体变形及地下水流动的数值分析-稳定流研究[J].煤炭学报,1998,23(6):289-294.BAI Mao,ELSWORTH D,LIU Tianquan.Nnmerical analysis of rock deformation and flow of underground water caused by coal extraction-stable flow[J].Journal of China Coal Society,1998,23(6):289-294.
[21]于不凡.开采解放层的认识与实践[M].北京:煤炭工业出版社,1986.
[22]张勇,许力峰,刘珂铭,等.采动煤岩体瓦斯通道形成机制及演化规律[J].煤炭学报,2012,37(9):1444-1450.ZHANG Yong,XU Lifeng,LIU Keming,et al.Formation mechanism and evolution laws of gas flow channel in mining coal and rock[J].Journal of China Coal Society,2012,37(9):1444-1450.
[23]王家臣,邵太升,赵洪宝,等.上保护层开采卸压释放作用数值模拟研究[A].和谐地球上的水工岩石力学-第三届全国水工岩石力学学术会议论文集[C].2010:182-186.
[24]翟成.近距离煤层群采动裂隙场与瓦斯流动场耦合规律及防治技术研究[D].徐州:中国矿业大学,2008:48-50.ZHAI Cheng.Research on coupling laws between facture field and gas flow field of short-distance coal seam group and preventive technology[D].Xuzhou:China University of Mining and Technology,2008:48-50.
[25]钱鸣高,许家林.覆岩采动裂隙分布的“O”形圈特征研究[J].煤炭学报,1998,23(5):20-23.QIAN Minggao,XU Jialin.Study on the“O-shape”circle distribution characteristics of mining induced fractures in the overlaying strata[J].Journal of China Coal Society,1998,23(5):466-469.
[26]王露,许家林,吴仁伦.采动煤层瓦斯充分卸压应力判别指标理论研究[J].煤炭科学技术,2012,40(3):1-5.WANG Lu,XU Jialin,WU Renlun.Theoretical study on stress distinguishing index of gas pressure fully released in mining seam[J].Coal Science and Technology,2012,40(3):1-5.
[27]中国矿业大学.长钻孔深部基点法测试装置[P].中国专利:CN201220233853.6,2012-12-26.