下台阶含仰拱一次开挖工法仰拱早期受力研究
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摘要
为明确下台阶含仰拱一次开挖工法仰拱早期的受力状态并制定相应的强度控制标准,以中条山隧道为依托工程,利用数值分析、位移-荷载反演等方法对仰拱早期在外荷载作用下的受力进行分析。下台阶含仰拱一次开挖工法中,仰拱随下台阶同步开挖,由于工法的特殊性,仰拱施作约2 h后会承受来自围岩变形、挖机及覆土自重产生的荷载。分析发现:3个部分荷载中围岩变形压力对仰拱早期受力影响最大,围岩变形作用下最大压应力产生于仰拱拱脚位置,上填覆土及扒碴机械重力作用会减小拱脚压应力,增大拱底压应力。多种外荷载共同作用时,仰拱压应力分布形态为"W"型,最大压应力产生于拱底,为0.14 MPa。考虑预留一定安全储备的情况下,该工法仰拱施作2 h时的抗压强度控制标准可按0.2 MPa进行设计。与传统台阶法仰拱早期受力特性对比,结果证明了一次开挖工法仰拱施作采用早高强混凝土的必要性。
The definition of early stress form of inverted arch when simultaneously excavated with lower bench and related control standards are very important. Hence,the early stress of inverted arch of Zhongtiaoshan Tunnel under the effect of external load is analyzed by numerical analysis,displacement-load inversion method,etc. The lower bench is simultaneously excavated with inverted arch,and due to the particularities of the method,the inverted arch will bear the load of surrounding rock deformation, excavation machine and cover soil weight after 2 hours of inverted arch construction. The analytical results show that the surrounding rock deformation greatly affects the stress on inverted arch;and the maximum compression stress induced by surrounding rock deformation occurs on inverted arch feet,while the weights of cover soil and excavation machine will reduce the compression stress on arch feet and increase the compression stress on crown bottom. The distribution of compression stress on crown top shows a W-shape,and the maximum compression stress of 0. 14 MPa occurs on crown bottom. The compression strength control standard could be 0. 2 MPa after 2 hours of inverted arch construction considering safety stock. The comparison results between the above-mentioned method and traditional one show that the using of early high-strength concrete for inverted arch construction is necessary.
The definition of early stress form of inverted arch when simultaneously excavated with lower bench and related control standards are very important. Hence,the early stress of inverted arch of Zhongtiaoshan Tunnel under the effect of external load is analyzed by numerical analysis,displacement-load inversion method,etc. The lower bench is simultaneously excavated with inverted arch,and due to the particularities of the method,the inverted arch will bear the load of surrounding rock deformation, excavation machine and cover soil weight after 2 hours of inverted arch construction. The analytical results show that the surrounding rock deformation greatly affects the stress on inverted arch;and the maximum compression stress induced by surrounding rock deformation occurs on inverted arch feet,while the weights of cover soil and excavation machine will reduce the compression stress on arch feet and increase the compression stress on crown bottom. The distribution of compression stress on crown top shows a W-shape,and the maximum compression stress of 0. 14 MPa occurs on crown bottom. The compression strength control standard could be 0. 2 MPa after 2 hours of inverted arch construction considering safety stock. The comparison results between the above-mentioned method and traditional one show that the using of early high-strength concrete for inverted arch construction is necessary.
引文
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[14]张德华,刘士海,任少强.隧道喷射混凝土强度增长规律及硬化速度对初期支护性能影响试验研究[J].岩土力学,2015(6):1708.ZHANG Dehua,LIU Shihai,REN Shaoqiang.Experimental study of effects of strength increase and hardening rate of shotcrete on its early supporting performances in tunneling[J].Rock and Soil Mechanics,2015(6):1708.
[15]ORESTE P P,PEILA D.Modelling progressive hardening of shotcrete in convergence-confinement approach to tunnel design[J].Railway Standard Design,1995(1):45.
[16]常燕庭.喷射混凝土早期材料性质对支护效果的影响[J].长江科学院院报,1992(3):8.CHANG Yanting.The influence of the early age properties of shotcrete on tunnel lining[J].Journal of Yangtze River Scientific Research Intitute,1992(3):8.
[17]刘艳青,卢汝绥.软岩隧道围岩压力的位移直接反演方法的研究[J].土木工程学报,2001,34(1):85.LIU Yanqing,LU Rusui.Study of reverse displacement method of ground pressure for tunnels in soft rock[J].China Civil Engineering Journal,2001,34(1):85.
[18]杨林德.岩土工程问题的反演理论与工程实践[M].北京:科学出版社,1996.YANG Linde.Inversion theory and engineering practice of geotechnical engineering problems[M].Beijing:Science Press,1996.
[19]刘英桀,张谢东,李佳莉,等.基于反分析法的浅埋隧道围岩应力释放率研究[J].武汉理工大学学报(交通科学与工程版),2015,39(6):1260.LIU Yingjie,ZHANG Xiedong,LI Jiali,et al.Study of rock stress release rate in shallow-buried tunnel based on displacement-back-analysis[J].Journal of Wuhan University of Technology(Transportation Science&Engineering),2015,39(6):1260.
[2]朱合华,刘学增.仰拱施工工序对隧道变形及结构内力的影响分析[C]//中国岩石力学与工程学会第六次学术大会论文集.北京:中国科学技术出版社,2000:675.ZHU Hehua,LIU Xuezeng.Influence of inverted arch construction sequence on deformation and internal force of tunnel lining[C]//Proceedings of the Sixth National Symposium on Rock Mechanics and Engineering.Beijing:China Science and Technology Press,2000:675.
[3]王宇,金爱兵,李兵.台阶法开挖隧道仰拱封闭距离效应研究[J].公路,2012(7):325.WANG Yu,JIN Aibing,LI Bing.Study of closure distance effect of inverted arch in bench method[J].Highway,2012(7):325.
[4]仇文革.隧道仰拱的施作时机与纵向效应的试验分析[J].西南交通大学学报,1993(6):68.QIU Wenge.Test analysis of the construction time and the longitudinal direction effect of the tunnel invert[J].Journal of Southwest Jiaotong University,1993(6):68.
[5]史继尧,王玥.仰拱步距和台阶长度对软岩大断面隧道稳定性影响分析[J].隧道建设,2017,37(4):428.SHI Jiyao,WANG Yue.Analysis of influence of invert arch step distance and bench length on stability of large crosssection soft rock tunnels[J].Tunnel Construction,2017,37(4):428.
[6]刘加敏.仰拱闭合距离对软弱围岩隧道施工变形控制研究[J].洛阳理工学院学报(自然科学版),2014(4):43.LIU Jiamin.Deformation control research on the influence of the inverted arch closing distance in soft surrounding tunnel construction[J].Journal of Luoyang Institute of Science and Technology(Natural Science Edition),2014(4):43.
[7]马赛.黄土隧道台阶法施工效应及技术参数研究[D].石家庄:石家庄铁道大学,2015.MA Sai.Study of construction effect and technical parameters of bench method in loess tunnel[D].Shijiazhuang:Shijiazhuang Tiedao University,2015.
[8]李文江,孙明磊,朱永全,等.软弱围岩隧道台阶法施工中拱脚稳定性及其控制技术[J].岩石力学与工程学报,2012(增刊1):2730.LI Wenjiang,SUN Minglei,ZHU Yongquan,et al.Arch spring stability and its control techniques during construction of tunnels with weak surrounding rocks by bench cut method[J].Chinese Journal of Rock Mechanics and Engineering,2012(S1):2730.
[9]周佳媚,李志业,高波.TBM施工隧道仰拱预制块的受力分析[J].中国铁道科学,2004,25(3):32.ZHOU Jiamei,LI Zhiye,GAO Bo.Mechanic analysis of invert prefabricate in TBM construction tunnel[J].China Railway Science,2004,25(3):32.
[10]杜明庆,张顶立,张素磊,等.高速铁路隧道仰拱结构受力现场实测分析[J].中国铁道科学,2017,38(5):53.DU Mingqing,ZHANG Dingli,ZHANG Sulei,et al.Field test and analysis of mechanical characteristics of tunnel invert structure for high-speed railway[J].China Railway Science,2017,38(5):53.
[11]肖支敏,任志华.基底状况对山岭隧道仰拱结构受力的影响研究[J].公路交通科技,2017(6):277.XIAO Zhimin,REN Zhihua.Effects of substrate condition on stress of inverted arch structure of mountain tunnel[J].Journal of Highway and Transportation Research and Development,2017(6):277.
[12]丁冬冬,梁庆国,徐善常,等.软化泥岩对隧道仰拱的受力特性影响研究[J].铁道科学与工程学报,2016,13(10):2001.DING Dongdong,LIANG Qingguo,XU Shanchang,et al.Test study of the mechanical characteristics of tunnel invert on softening mudstone section[J].Journal of Railway Science and Engineering,2016,13(10):2001.
[13]铁路隧道设计规范:TB 10003—2016[S].北京:中国铁道出版社,2017.Code for design of railway tunnel:TB 10003-2016[S].Beijing:China Railway Publishing House,2017.
[14]张德华,刘士海,任少强.隧道喷射混凝土强度增长规律及硬化速度对初期支护性能影响试验研究[J].岩土力学,2015(6):1708.ZHANG Dehua,LIU Shihai,REN Shaoqiang.Experimental study of effects of strength increase and hardening rate of shotcrete on its early supporting performances in tunneling[J].Rock and Soil Mechanics,2015(6):1708.
[15]ORESTE P P,PEILA D.Modelling progressive hardening of shotcrete in convergence-confinement approach to tunnel design[J].Railway Standard Design,1995(1):45.
[16]常燕庭.喷射混凝土早期材料性质对支护效果的影响[J].长江科学院院报,1992(3):8.CHANG Yanting.The influence of the early age properties of shotcrete on tunnel lining[J].Journal of Yangtze River Scientific Research Intitute,1992(3):8.
[17]刘艳青,卢汝绥.软岩隧道围岩压力的位移直接反演方法的研究[J].土木工程学报,2001,34(1):85.LIU Yanqing,LU Rusui.Study of reverse displacement method of ground pressure for tunnels in soft rock[J].China Civil Engineering Journal,2001,34(1):85.
[18]杨林德.岩土工程问题的反演理论与工程实践[M].北京:科学出版社,1996.YANG Linde.Inversion theory and engineering practice of geotechnical engineering problems[M].Beijing:Science Press,1996.
[19]刘英桀,张谢东,李佳莉,等.基于反分析法的浅埋隧道围岩应力释放率研究[J].武汉理工大学学报(交通科学与工程版),2015,39(6):1260.LIU Yingjie,ZHANG Xiedong,LI Jiali,et al.Study of rock stress release rate in shallow-buried tunnel based on displacement-back-analysis[J].Journal of Wuhan University of Technology(Transportation Science&Engineering),2015,39(6):1260.