一种无中导洞连拱隧道衬砌开裂原因分析及结构优化
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摘要
为解决传统连拱隧道中导洞法施工工序繁琐、结构受力转换复杂等问题,云南某隧道采用了一种无中导洞连拱隧道,其后行洞钢拱架焊接于先行洞钢拱架,使初期支护相互搭接形成了连拱隧道中墙,从而避免了中导洞开挖,但在隧道施工中,先行洞二次衬砌左侧起拱线至左拱腰出现了大量纵向与斜向裂缝。结合隧道实际地质和施工状况,运用Flac3d建立了地层-隧道结构数值模型,研究分析了初期支护各自独立封闭成环和初期支护搭接处界面特性对无中导洞连拱隧道衬砌开裂的影响。结果表明:后行洞初期支护独立闭合成环时,即使初支结构之间产生了一定的滑移,隧道衬砌结构仍处于安全状态;后行洞初期支护未独立闭合成环时,搭接处会产生较大的相对滑移,初期支护承载力不能充分发挥,难以有效控制围岩变形和塑性区发展,先行洞二次衬砌承受了较大的围岩荷载,其左拱腰内侧边缘拉应力远超过了衬砌混凝土的抗拉强度,由此造成了左拱腰处衬砌开裂。因此,为避免无中导洞连拱隧道衬砌出现裂缝,建议在设计中应使连拱隧道初期支护各自独立闭合成环,合理加强中墙位置初期支护结构,施工中对关键施工环节、关键受力部位采取有效控制措施,保证支护结构的整体承载力。
To solve the problems of complicated construction process and complicated structural force transformation in the middle drift method used in traditional multi-arch tunnel,a multi-arch tunnel without middle drift has been applied in a tunnel in Yunnan Province.Its following hole steel arch frame is welded to the front hole steel arch frame,so that the primary supports can overlap each other to form the middle wall of the tunnel,avoiding the excavation of middle drift.However,there are a large number of longitudinal and oblique cracks ranging from springing line to left hance in the left side of secondary lining of front hole during construction.According to the actual geology and construction situation of the tunnel,the numerical model of formation-tunnel structure is established by using Flac3 d.The influences of the primary support with freestanding closed loop and the interface characteristics at lap joint of primary support on lining cracking in multi-arch tunnel without middle drift are analysed.The result shows that(1) the lining is still in a safe state when the primary support of the following hole with independently freestanding closed loop,even if a certain slip occurred between the primary support structures;(2) when the primary support of the following hole without non-freestanding closed loop,a large relative slip may occur at the connection position.Thereby,the primary support cannot fully exert the bearing capacity and effectively control the deformation of the surrounding rock and the development of plastic zone.Subjected to heavy surrounding rock loads, the secondary lining of the front hole cracked because the tensile stress at the inner edge of the left hance far exceeded the tensile strength of concrete.In order to prevent the lining cracks in the tunnel,it is suggested to design the freestanding close loop primary support and reasonably strengthen the primary support structure of the middle wall.Moreover,to take effective control measures in key construction links and key stress parts can ensure the overall bearing capacity of the support structure.
To solve the problems of complicated construction process and complicated structural force transformation in the middle drift method used in traditional multi-arch tunnel,a multi-arch tunnel without middle drift has been applied in a tunnel in Yunnan Province.Its following hole steel arch frame is welded to the front hole steel arch frame,so that the primary supports can overlap each other to form the middle wall of the tunnel,avoiding the excavation of middle drift.However,there are a large number of longitudinal and oblique cracks ranging from springing line to left hance in the left side of secondary lining of front hole during construction.According to the actual geology and construction situation of the tunnel,the numerical model of formation-tunnel structure is established by using Flac3 d.The influences of the primary support with freestanding closed loop and the interface characteristics at lap joint of primary support on lining cracking in multi-arch tunnel without middle drift are analysed.The result shows that(1) the lining is still in a safe state when the primary support of the following hole with independently freestanding closed loop,even if a certain slip occurred between the primary support structures;(2) when the primary support of the following hole without non-freestanding closed loop,a large relative slip may occur at the connection position.Thereby,the primary support cannot fully exert the bearing capacity and effectively control the deformation of the surrounding rock and the development of plastic zone.Subjected to heavy surrounding rock loads, the secondary lining of the front hole cracked because the tensile stress at the inner edge of the left hance far exceeded the tensile strength of concrete.In order to prevent the lining cracks in the tunnel,it is suggested to design the freestanding close loop primary support and reasonably strengthen the primary support structure of the middle wall.Moreover,to take effective control measures in key construction links and key stress parts can ensure the overall bearing capacity of the support structure.
引文
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[13] 谢春华.无中导洞城市连拱隧道施工工法分析研究 [J].中外公路,2017,37(4):214-218.XIE Chun-hua.Analysis and Study on Construction Methods of Urban Double-arch Tunnel without Pilot Hole [J].Journal of China & Foreign Highway,2017,37(4):214-218.
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[15] 赖金星,谢永利,李宁军.无中导洞施工双连拱隧道的数值模拟分析 [J].水文地质工程地质,2006(3):68-71.LAI Jin-xing,XIE Yong-li,LI Ning-jun.Numerical Simulation of Multi-arch Highway Tunnel Constructed without Advancing Middle Drift[J].Hydrogeology & Engineering Geology,2006(3):68-71.
[16] 云南省交通规划设计研究院.国家高速公路网G0613云南省香格里拉至丽江高速公路第10标段K82+200-K94+200两阶段施工图设计 [R].昆明:云南省交通规划设计研究院,2015.Broadvision Engineering Consultants.Two-phase Construction Drawing Design of 10th Tender K82+200-K94+200 Section for National Expressway Network G0613 in Yunnan Provincial Shangrila-Lijiang Expressway [R].Kunming:Broadvision Engineering Consultants,2015.
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[2] 邹育麟,何川,周艺,等.重庆高速公路现役营运隧道渗漏水病害统计及成因分析 [J].公路交通科技,2013,30(1):86-93,101.ZOU Yu-lin,HE Chuan,ZHOU Yi,et al.Statistics and Cause Analysis of Leakage Diseases in Operating Expressway Tunnels in Chongqing[J].Journal of Highway and Transportation Research and Development,2013,30(1):86-93,101.
[3] 张永兴,阳军生,晏莉.某浅埋偏压连拱隧道二衬开裂原因分析 [J].长沙理工大学学报:自然科学版,2007,4(3):44-48.ZHANG Yong-xing,YANG Jun-sheng,YAN Li.Reasons Why the Second Lining of One Shallow Asymmetry Doublearch Tunnel Cracks[J].Journal of Changsha University of Science and Technology:Natural Science Edition,2007,4(3):44-48.
[4] 付黎龙.偏压连拱隧道衬砌病害分析及加固研究 [D].长沙:中南大学,2009.FU Li-long.Disease Analysis and Reinforcement of Bias Arch Tunnel Lining[D].Changsha:Central South University,2009.
[5] 张国庆.无中墙连拱隧道结构研究 [D].重庆:重庆交通大学,2010.ZHANG Guo-qing.Structure of Double-arch Tunnel without Middle-wall [D].Chongqing:Chongqing Jiaotong University,2010.
[6] 陈力华.无中导洞连拱隧道设计施工技术探讨 [J].公路交通技术,2012 (1):94-98.CHEN Li-hua.Probe into Design and Construction Techniques for Multi-arch Tunnels without Middle Drifts[J].Technology of Highway and Transport,2012 (1):94-98.
[7] 舒磊.无导洞法施工连拱隧道技术 [J].铁道标准设计,2008 (6):76-79.SHU Lei.Construction Technology of Multi-arch Tunnel without Middle Drift[J].Railway Standard Design,2008 (6):76-79.
[8] 刘生,李宁军,刘红平.基于无导洞方法的连拱隧道结构设计与施工研究 [J].水利与建筑工程学报,2010,8(4):107-110.LIU Sheng,LI Ning-jun,LIU Hong-ping.Research on Structural Design and Construction Scheme for Multi-arch Tunnel in Construction without Pilot[J].Journal of Water Resources and Architectural Engineering,2010,8(4):107-110.
[9] 赖金星,谢永利,李华.连拱隧道无中导洞施工技术探讨 [J].铁道建筑,2006 (4):34-35,43.LAI Jin-xing,XIE Yong-li,LI Hua.Probe into Construction Techniques for Multi-arch Tunnel without Middle Drift[J].Railway Engineering,2006 (4):34-35,43.
[10] 张万斌,李海军,王明年.喷筑隐式异型中墙复合式连拱隧道的设计分析 [J].现代隧道技术,2013,50(6):147-151.ZHANG Wan-bin,LI Hai-jun,WANG Ming-nian.Design and Analysis of a Double-arch Tunnel with Concealed,Sprayed Irregular-Composite Mid-wall[J].Modern Tunnelling Technology,2013,50(6):147-151.
[11] 李海军,王明年,张万斌.隐式中墙连拱隧道工法探讨 [J].隧道建设,2015,35(12):1271-1274.LI Hai-jun,WANG Ming-nian,ZHANG Wan-bin.Discussion on Construction Method for Double-arch Tunnel with Concealed Central Wall[J].Tunnel Construction,2015,35(12):1271-1274.
[12] 李海军.隐式中墙连拱隧道对称中隔壁工法设计与分析 [J].重庆建筑,2015,14(6):40-42.LI Hai-jun.Design and Analysis of Symmetrical Temporary Middle Wall Method for Double-arch Tunnel with Concealed Center Wall[J].Chongqing Architecture,2015,14(6):40-42.
[13] 谢春华.无中导洞城市连拱隧道施工工法分析研究 [J].中外公路,2017,37(4):214-218.XIE Chun-hua.Analysis and Study on Construction Methods of Urban Double-arch Tunnel without Pilot Hole [J].Journal of China & Foreign Highway,2017,37(4):214-218.
[14] 洪永佳.软弱围岩下无中导洞复墙式连拱隧道施工三维数值模拟分析 [J].福建交通科技,2017 (3):58-61.HONG Yong-jia.3D Numerical Simulation of Multi-arch Tunnel without Middle Drift in Weak Surrounding Rock[J].Fujian Transport Science and Technology,2017(3):58-61.
[15] 赖金星,谢永利,李宁军.无中导洞施工双连拱隧道的数值模拟分析 [J].水文地质工程地质,2006(3):68-71.LAI Jin-xing,XIE Yong-li,LI Ning-jun.Numerical Simulation of Multi-arch Highway Tunnel Constructed without Advancing Middle Drift[J].Hydrogeology & Engineering Geology,2006(3):68-71.
[16] 云南省交通规划设计研究院.国家高速公路网G0613云南省香格里拉至丽江高速公路第10标段K82+200-K94+200两阶段施工图设计 [R].昆明:云南省交通规划设计研究院,2015.Broadvision Engineering Consultants.Two-phase Construction Drawing Design of 10th Tender K82+200-K94+200 Section for National Expressway Network G0613 in Yunnan Provincial Shangrila-Lijiang Expressway [R].Kunming:Broadvision Engineering Consultants,2015.
[17] Itasca Consulting Group Inc.FLAC3D User's Manual [R].Version 5.01.Minneapolis:Itasca Consulting Group Inc.,2013.
[18] GB 50010—2010,混凝土结构设计规范 [S].GB 50010—2010,Code for Design of Concrete Structures [S].