综采工作面基本顶厚跨比对其初次断裂失稳影响规律
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摘要
综采工作面基本顶初次断裂失稳机理对工作面支架选型及采场围岩稳定性控制至关重要。通过建立顶板力学模型分析得出:综采工作面基本顶初次断裂前,基本顶厚跨比从初始状态减小趋近极限状态时,其内部最大主应力σ1与最大剪应力τmax均逐渐增加;当厚跨比接近0. 2时,σ1与τmax均出现陡增,但σ1增加速率大于τmax,易在基本顶两端顶部发生断裂,且基本顶初次断裂时极限厚跨比n1一般大于0. 2。在不发生滑落失稳条件下,基本顶极限厚跨比n1随回转角θ的增大近似呈线性增加;证明了基本顶铰接结构回转初期(θ为0°～3°)易发生滑落失稳。在仅考虑厚跨比影响的条件下,基本顶铰接结构发生回转失稳的临界条件为极限厚跨比n1=0. 624。然而,当n1<0. 624时,回转极限平衡角大于岩块回转平衡角所允许的最小值时,亦会造成铰接结构回转失稳。同时,在考虑支架弹性变形的基础上,建立了基本顶铰接结构滑落失稳对工作面支架动载系数计算方法,当直接顶与基本顶离层量Δh为0时,动载系数Fsd取最小值;Δh不为0时,Fsd随Δh增加而增大,但随直接顶与支架刚度之比、直接顶自重与基本顶传递载荷之比增加而减少。最后,通过对不同综采工作面初次来压时支架工作阻力与动载系数进行计算,验证了理论分析的有效性。
The mechanism of the initial fracture instability of main roof in a fully mechanized longwall face is critical to the selection of hydraulic support and the control of surrounding rock. The fracture process and structural instability mechanism of main roof were analyzed by establishing the roof fracture mechanical model.The results show that the internal maximum principal stress σ1 and the maximum shear stress τmaxincrease gradually,with the decrease of the thickness-span ratio of main roof from the initial state to the limit state.When the thickness-span ratio is close to 0.2,both σ1 and τmaxincrease sharply,but the increase rate of σ1 is greater than that of τmax,and the main roof is thus easy to break at the top of both ends.The limit thickness-span ratio n1 of main roof is normally greater than 0.2 when theinitial fracture appears at the main roof.The n1 of hinge structure of main roof that does not appear sliding instability increases linearly with the increase of the rotation angle θ.The hinge structure is easy to occur sliding instability at the beginning of the initial rotation when the rotation angle is 0° ～ 3°. The critical value of the rotation instability of the hinge structure is n1 equals to 0.624 on a condition that only the roof thickness-span ratio dominates.When the n1 is less than 0.624,however,the rotation limit balance angle βjbecomes larger than the minimum value β1 allowed by the swing balance angle,and the hinge structure occurs rotation instability.In addition,the method for determining the dynamic load factor of the longwall face when the main roof structure appears slipping instability was obtained.When the separation layer Δh between immediate roof and main roof is 0,the minimum value of the dynamic load factor Fsd should be applied.When Δh is non-zero,Fsdincreases with the increase of Δh,but also can be reduced with the increase of the ratio of immediate roof to support stiffness ks,the ratio of immediate roof weight to main roof transfer load m.Finally,the liability of the theoretical analysis was verified by the analytical calculations for the initial weighting of different fully mechanized longwall faces.
The mechanism of the initial fracture instability of main roof in a fully mechanized longwall face is critical to the selection of hydraulic support and the control of surrounding rock. The fracture process and structural instability mechanism of main roof were analyzed by establishing the roof fracture mechanical model.The results show that the internal maximum principal stress σ1 and the maximum shear stress τmaxincrease gradually,with the decrease of the thickness-span ratio of main roof from the initial state to the limit state.When the thickness-span ratio is close to 0.2,both σ1 and τmaxincrease sharply,but the increase rate of σ1 is greater than that of τmax,and the main roof is thus easy to break at the top of both ends.The limit thickness-span ratio n1 of main roof is normally greater than 0.2 when theinitial fracture appears at the main roof.The n1 of hinge structure of main roof that does not appear sliding instability increases linearly with the increase of the rotation angle θ.The hinge structure is easy to occur sliding instability at the beginning of the initial rotation when the rotation angle is 0° ～ 3°. The critical value of the rotation instability of the hinge structure is n1 equals to 0.624 on a condition that only the roof thickness-span ratio dominates.When the n1 is less than 0.624,however,the rotation limit balance angle βjbecomes larger than the minimum value β1 allowed by the swing balance angle,and the hinge structure occurs rotation instability.In addition,the method for determining the dynamic load factor of the longwall face when the main roof structure appears slipping instability was obtained.When the separation layer Δh between immediate roof and main roof is 0,the minimum value of the dynamic load factor Fsd should be applied.When Δh is non-zero,Fsdincreases with the increase of Δh,but also can be reduced with the increase of the ratio of immediate roof to support stiffness ks,the ratio of immediate roof weight to main roof transfer load m.Finally,the liability of the theoretical analysis was verified by the analytical calculations for the initial weighting of different fully mechanized longwall faces.
引文
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[12]侯忠杰.断裂带老顶的判别准则及在浅埋煤层中的应用[J].煤炭学报,2003,28(1):8-12.HOU Zhongjie.The criterion on determining main roof in breaking zone and its application to the shallow seam[J]. Journal of China Coal Society,2003,28(1):8-12.
[13]杨登峰,陈忠辉,洪钦锋,等.浅埋煤层开采顶板切落压架灾害的突变分析[J].采矿与安全工程学报,2016,33(1):122-127.YANG Dengfeng,CHEN Zhonghui,HONG Qinfeng,et al. Catastrophic analysis of support crushing disasters while roof cutting in shallow seam mining[J].Journal of Mining and Safety Engineering,2016,33(1):122-127.
[14]杨登峰,陈忠辉,朱帝杰,等.基于顶板切落的浅埋煤层开采支架工作阻力研究[J].岩土工程学报,2016,38(S2):286-292.YANG Dengfeng,CHEN Zhonghui,ZHU Dijie,et al.Support capacity at roof cutting in mining of shallow coal seam[J].Chinese Journal of Geotechnical Engineering,2016,38(S2):286-292.
[15]赵雁海,宋选民.浅埋超长工作面裂隙梁铰拱结构稳定性分析及数值模拟研究[J].岩土力学,2016,37(1):203-209.ZHAO Yanhai,SONG Xuanmin. Stability analysis and numerical simulation of hinged arch structure for fractured beam in superlong mining workface under shallow seam[J]. Rock and Soil Mechanics,2016,37(1):203-209.
[16] BAKUN MAZOR D,HATZOR Y H,DERSHOWITZ W S.Modeling mechanical layering effects on stability of underground openings in jointed sedimentary rocks[J].International Journal of Rock Mechanics&Mining Sciences,2009,46(2):262-271.
[17]王家臣,王兆会.浅埋薄基岩高强度开采工作面初次来压基本顶结构稳定性研究[J].采矿与安全工程学报,2015,32(2):175-181.WANG Jiachen,WANG Zhaohui. Stability of main roof structure during the first weighting in shallow high-intensity mining face with thin bedrock[J]. Journal of Mining and Safety Engineering,2015,32(2):175-181.
[18] WANG Jiachen,YANG Shengli,LI Yang,et al.A dynamic method to determine the supports capacity in longwall coal mining[J]. International Journal of Surface Mining Reclamation&Environment,2015,29(4):277-288.
[19]伊康,弓培林,刘畅.浅埋薄表土层薄基岩综放工作面覆岩结构及顶板控制[J].煤炭学报,2018,43(5):1230-1237.YI Kang,GONG Peilin,LIU Chang. Overlying strata structures and roof control of working face under thin topsoil and thin bedrock in shallow seam[J]. Journal of China Coal Society,2018,43(5):1230-1237.
[20]陈忠辉,张凌凡,杨登峰,等.浅埋煤层开采顶板切落条件下支架动载效应[J].煤炭学报,2017,42(2):322-327.CHEN Zhonghui,ZHANG Lingfan,YANG Dengfeng,et al.Dynamic loading effect of support while roof cutting in shallow coal seam mining[J].Journal of China Coal Society,2017,42(2):322-327.
[21]王先.超静定梁的弹性力学解法[J].青海师范大学学报(自科版),2002(2):30-33.WANG Xian. Analytical solution for hyper static beam[J]. Journal of Qinghai Normal University(Natural Science),2002(2):30-33.
[22]李建伟.西部浅埋厚煤层高强度开采覆岩导气裂缝的时空演化机理及控制研究[D].徐州:中国矿业大学,2017.LI Jianwei.Spatial-temporal evolution mechanism and control technology of air leakage fissures in high-intensity mining of shallow thick coal seam[D]. Xuzhou:China University of Mining and Technology,2017.
[23]孙训方,方孝淑,关来泰.材料力学[M].北京:高等教育出版社,2009.
[24]付玉平,宋选民,邢平伟,等.大采高采场顶板断裂关键块稳定性分析[J].煤炭学报,2009,34(8):1027-1031.FU Yuping,SONG Xuanmin,XING Pingwei,et al.Stability analysis on main roof key block in large mining height workface[J].Journal of China Coal Society,2009,34(8):1027-1031.
[25]沈滨和.浅埋煤层大采高工作面顶板结构及支护阻力分析[D].西安:西安科技大学,2016.SHEN Binhe. Research on roof structure and support resistance of large mining height working face in shallow seam[D]. Xi’an:Xi’an University of Science and Technology,2016.
[26]周金龙.浅埋煤层大采高综采工作面顶板结构及支架载荷研究[D].西安:西安科技大学,2017.ZHOU Jinlong.Research on roof structure and support load of fully mechanized coal face with mining height in shallow coal seam[D].Xi’an:Xi’an University of Science and Technology,2017.
[2]黄庆享,祈万涛,杨春林.采场老顶初次破断机理与破断形态分析[J].西安科技大学学报,1999,19(3):193-197.HUANG Qingxiang,QI Wantao,YANG Chunlin. Analysis of mechanism and form of main roof breaking during first weighting in longwall face[J].Journal of Xi’an University of Science and Technology,1999,19(3):193-197.
[3]黄庆享.采场老顶初次来压的结构分析[J].岩石力学与工程学报,1998,17(5):521-526.HUANG Qingxiang. Structural analysis of main roof stability during first weighting in longwall face[J].Chinese Journal of Rock Mechanics and Engineering,1998,17(5):521-526.
[4]许斌,蒋金泉,代进,等.采场上覆关键层破断角的力学推导和实验模拟[J].煤炭学报,2018,43(3):599-606.XU Bin,JIANG Jinquan,DAI Jin,et al. Mechanical derivation and experimental simulation of breaking angle of key strata in overlying strata[J].Journal of China Coal Society,2018,43(3):599-606.
[5]康建荣,王金庄.采动覆岩力学模型及断裂破坏条件分析[J].煤炭学报,2002,27(1):16-20.KANG Jianrong,WANG Jinzhuang. The mechanical model of the overburden rock under mining and the broken condition analysis[J].Journal of China Coal Society,2002,27(1):16-20.
[6]刘学生,宁建国,谭云亮.近浅埋煤层顶板破断力学模型研究[J].采矿与安全工程学报,2014,31(2):214-219.LIU Xuesheng,NING Jianguo,TAN Yunliang. Study on roof breaking model of near shallow seam[J].Journal of Mining and Safety Engineering,2014,31(2):214-219.
[7]王红卫,陈忠辉,杜泽超,等.弹性薄板理论在地下采场顶板变化规律研究中的应用[J].岩石力学与工程学报,2006,25(S2):3769-3774.WANG Hongwei,CHEN Zhonghui,DU Zechao,et al. Application of elastic thin plate theory to change rule of roof in underground stope[J]. Chinese Journal of Rock Mechanics and Engineering,2006,25(S2):3769-3774.
[8]薛熠,滕腾,王希贺,等.采场顶板破断模型及垮落规律分析[J].科学技术与工程,2016,16(7):156-161.XUE Yi,TENG Teng,WANG Xihe,et al.Analysis of fracturing model and caving law of stope roof[J]. Science Technology and Engineering,2016,16(7):156-161.
[9]王新丰,高明中.变长工作面采场顶板破断机理的力学模型分析[J].中国矿业大学学报,2015,44(1):36-45.WANG Xinfeng,GAO Mingzhong. Mechanical model of fracture mechanism of stope roof for working face with variable length[J]. Journal of China University of Mining&Technology,2015,44(1):36-45.
[10]谢生荣,陈冬冬,孙颜顶,等.基本顶弹性基础边界薄板模型分析(Ⅰ)—初次破断[J].煤炭学报,2016,41(6):1360-1368.XIE Shengrong,CHEN Dongdong,SUN Yanding,et al. Analysis on thin plate model of basic roof at elastic foundation boundary(I):First breaking[J]. Journal of China Coal Society,2016,41(6):1360-1368.
[11]钱鸣高,缪协兴,何富连.采场"砌体梁"结构的关键块分析[J].煤炭学报,1994,19(6):557-563.QIAN Minggao,MIAO Xiexing,HE Fulian. Analysis of key block in the structure of voussoir beam in longwall mining[J]. Journal of China Coal Society,1994,19(6):557-563.
[12]侯忠杰.断裂带老顶的判别准则及在浅埋煤层中的应用[J].煤炭学报,2003,28(1):8-12.HOU Zhongjie.The criterion on determining main roof in breaking zone and its application to the shallow seam[J]. Journal of China Coal Society,2003,28(1):8-12.
[13]杨登峰,陈忠辉,洪钦锋,等.浅埋煤层开采顶板切落压架灾害的突变分析[J].采矿与安全工程学报,2016,33(1):122-127.YANG Dengfeng,CHEN Zhonghui,HONG Qinfeng,et al. Catastrophic analysis of support crushing disasters while roof cutting in shallow seam mining[J].Journal of Mining and Safety Engineering,2016,33(1):122-127.
[14]杨登峰,陈忠辉,朱帝杰,等.基于顶板切落的浅埋煤层开采支架工作阻力研究[J].岩土工程学报,2016,38(S2):286-292.YANG Dengfeng,CHEN Zhonghui,ZHU Dijie,et al.Support capacity at roof cutting in mining of shallow coal seam[J].Chinese Journal of Geotechnical Engineering,2016,38(S2):286-292.
[15]赵雁海,宋选民.浅埋超长工作面裂隙梁铰拱结构稳定性分析及数值模拟研究[J].岩土力学,2016,37(1):203-209.ZHAO Yanhai,SONG Xuanmin. Stability analysis and numerical simulation of hinged arch structure for fractured beam in superlong mining workface under shallow seam[J]. Rock and Soil Mechanics,2016,37(1):203-209.
[16] BAKUN MAZOR D,HATZOR Y H,DERSHOWITZ W S.Modeling mechanical layering effects on stability of underground openings in jointed sedimentary rocks[J].International Journal of Rock Mechanics&Mining Sciences,2009,46(2):262-271.
[17]王家臣,王兆会.浅埋薄基岩高强度开采工作面初次来压基本顶结构稳定性研究[J].采矿与安全工程学报,2015,32(2):175-181.WANG Jiachen,WANG Zhaohui. Stability of main roof structure during the first weighting in shallow high-intensity mining face with thin bedrock[J]. Journal of Mining and Safety Engineering,2015,32(2):175-181.
[18] WANG Jiachen,YANG Shengli,LI Yang,et al.A dynamic method to determine the supports capacity in longwall coal mining[J]. International Journal of Surface Mining Reclamation&Environment,2015,29(4):277-288.
[19]伊康,弓培林,刘畅.浅埋薄表土层薄基岩综放工作面覆岩结构及顶板控制[J].煤炭学报,2018,43(5):1230-1237.YI Kang,GONG Peilin,LIU Chang. Overlying strata structures and roof control of working face under thin topsoil and thin bedrock in shallow seam[J]. Journal of China Coal Society,2018,43(5):1230-1237.
[20]陈忠辉,张凌凡,杨登峰,等.浅埋煤层开采顶板切落条件下支架动载效应[J].煤炭学报,2017,42(2):322-327.CHEN Zhonghui,ZHANG Lingfan,YANG Dengfeng,et al.Dynamic loading effect of support while roof cutting in shallow coal seam mining[J].Journal of China Coal Society,2017,42(2):322-327.
[21]王先.超静定梁的弹性力学解法[J].青海师范大学学报(自科版),2002(2):30-33.WANG Xian. Analytical solution for hyper static beam[J]. Journal of Qinghai Normal University(Natural Science),2002(2):30-33.
[22]李建伟.西部浅埋厚煤层高强度开采覆岩导气裂缝的时空演化机理及控制研究[D].徐州:中国矿业大学,2017.LI Jianwei.Spatial-temporal evolution mechanism and control technology of air leakage fissures in high-intensity mining of shallow thick coal seam[D]. Xuzhou:China University of Mining and Technology,2017.
[23]孙训方,方孝淑,关来泰.材料力学[M].北京:高等教育出版社,2009.
[24]付玉平,宋选民,邢平伟,等.大采高采场顶板断裂关键块稳定性分析[J].煤炭学报,2009,34(8):1027-1031.FU Yuping,SONG Xuanmin,XING Pingwei,et al.Stability analysis on main roof key block in large mining height workface[J].Journal of China Coal Society,2009,34(8):1027-1031.
[25]沈滨和.浅埋煤层大采高工作面顶板结构及支护阻力分析[D].西安:西安科技大学,2016.SHEN Binhe. Research on roof structure and support resistance of large mining height working face in shallow seam[D]. Xi’an:Xi’an University of Science and Technology,2016.
[26]周金龙.浅埋煤层大采高综采工作面顶板结构及支架载荷研究[D].西安:西安科技大学,2017.ZHOU Jinlong.Research on roof structure and support load of fully mechanized coal face with mining height in shallow coal seam[D].Xi’an:Xi’an University of Science and Technology,2017.