浅埋软岩公路隧道超前管棚支护机制与工程应用研究
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摘要
根据弹性理论刚度等效方法,管棚可视作加劲肋,加固岩土视作各项同性板,将隧道拱顶局部范围的管棚和加固岩土整体视为弹性地基上四边受特定约束的各向异性板。基于传统的管棚弹性地基梁模型,建立管棚弹性地基各向异性板模型,将管棚的力学模型从一维拓展至二维,采用COMSOLPDE有限元法求解,并应用该模型分析甸头隧道管棚的作用机制。同时开展隧道室内物理模型试验,研究超前管棚作用机制,对比分析工程中常用的Φ76 mm和Φ108 mm两种管棚的支护效果,研究结果表明:(1)管棚的受力和变形主要集中在掌子面前6 m范围内,将Φ76 mm管棚调整为Φ108 mm管棚后,横向和轴向弯矩分别增大56.9%和5.5%,同时管棚最大挠度降低38%,表明管棚支护刚度越大,所需承担的隧道开挖过程中的上部荷载也越大,通过减少上部围岩的松弛变形和应力释放,有效控制围岩变形。(2)由于管棚弹性地基各向异性板模型是二维的,对比分析管棚模型的横向和轴向弯矩发现,Φ76 mm和Φ108 mm管棚的轴向弯矩分别为横向弯矩的13和20倍,说明管棚沿隧道轴向弯矩作用明显,与已有研究结论相符,但横向弯矩作用同样不可忽略。(3)室内模型试验表明,沿隧道横向,管棚和围岩共同形成一定厚度的环向承载结构,起到超前支护的作用,共同承担隧道开挖后上方围岩荷载;沿隧道轴向,管棚与初支结构形成系统进行承载,起到梁支撑的作用,有效控制上方围岩的松弛变形和应力释放,从而提高掌子面围岩的稳定性。应用上述研究成果,成功指导了云南大永高速公路大断面软岩公路隧道下穿既有公路工程,将Φ76 mm管棚方案调整为Φ108 mm管棚方案后,现场实测拱顶上方最大地表沉降值减少了38%,室内试验的减少值为37%,室内试验和现场监测分析结果进一步验证了该模型的可行性和合理性,保障了整个下穿施工过程的安全顺利。
According to the equivalent stiffness method of elastic theory,pipe-roofs can be regarded as stiffening rib and reinforced rock can be regarded as an isotropic plate. The reinforced rock and pipe-roofs can be considered as an anisotropic plate on elastic foundation with specific constraints on the four edges. The model of anisotropic plate on elastic foundation is established and solved by finite element method-COMSOL PDE. The mechanic behaviors of pipe-roofs are analyzed. The supporting effects of two commonly used types of pipe-roofs(Φ76 mm and Φ108 mm) are compared and analyzed based on the model tests' result. The research shows that:(1) the stress and deformation of the grouting stabilization area mainly appear in the section no more than 6 m ahead of the working face. After adjusting Φ76 mm pipe-roof to Φ108 mm pipe-roof,My and Mx increase by 56.9% and 5.5%respectively,while the maximum deflection decreases by 38%. It shows that the greater the stiffness of pipe-roof support,the more upper load it needs to bear. So the deformation of surrounding rock can be effectively controlled by reducing the relaxation deformation and stress release of the upper surrounding rock. My of Φ108 mm and Φ76 mm pipe-roof are 13 and 20 times the size of Mx respectively,which indicates that the pipe-roof has obvious effect on My along the tunnel. But the Mx can not be neglected. Model tests show that a bearing arch is formed with the pipe-roof and the surrounding rock to bear the upper load during the tunnel's excavation. Along the longitudinal direction of the tunnel,the pipe-roof plays a role of supporting beam to reduce the rock mass's deformation and the stress release and improve the stabilization of the working face.The achievements are successfully applied in the shallow buried tunnel's construction. The tunnel's section is large,and the surrounding rock mass is very weak,and an existing highway project stands nearly. After adjusting Φ76 mm pipe-roof scheme to Φ108 mm pipe-roof scheme,the maximum surface settlement monitored in the field decreased by 38% and that of the indoor test decreased by 37%. The engineering application shows that the tunnel's construction is safe and the achievements are reasonable.
According to the equivalent stiffness method of elastic theory,pipe-roofs can be regarded as stiffening rib and reinforced rock can be regarded as an isotropic plate. The reinforced rock and pipe-roofs can be considered as an anisotropic plate on elastic foundation with specific constraints on the four edges. The model of anisotropic plate on elastic foundation is established and solved by finite element method-COMSOL PDE. The mechanic behaviors of pipe-roofs are analyzed. The supporting effects of two commonly used types of pipe-roofs(Φ76 mm and Φ108 mm) are compared and analyzed based on the model tests' result. The research shows that:(1) the stress and deformation of the grouting stabilization area mainly appear in the section no more than 6 m ahead of the working face. After adjusting Φ76 mm pipe-roof to Φ108 mm pipe-roof,My and Mx increase by 56.9% and 5.5%respectively,while the maximum deflection decreases by 38%. It shows that the greater the stiffness of pipe-roof support,the more upper load it needs to bear. So the deformation of surrounding rock can be effectively controlled by reducing the relaxation deformation and stress release of the upper surrounding rock. My of Φ108 mm and Φ76 mm pipe-roof are 13 and 20 times the size of Mx respectively,which indicates that the pipe-roof has obvious effect on My along the tunnel. But the Mx can not be neglected. Model tests show that a bearing arch is formed with the pipe-roof and the surrounding rock to bear the upper load during the tunnel's excavation. Along the longitudinal direction of the tunnel,the pipe-roof plays a role of supporting beam to reduce the rock mass's deformation and the stress release and improve the stabilization of the working face.The achievements are successfully applied in the shallow buried tunnel's construction. The tunnel's section is large,and the surrounding rock mass is very weak,and an existing highway project stands nearly. After adjusting Φ76 mm pipe-roof scheme to Φ108 mm pipe-roof scheme,the maximum surface settlement monitored in the field decreased by 38% and that of the indoor test decreased by 37%. The engineering application shows that the tunnel's construction is safe and the achievements are reasonable.
引文
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[2]MIWA M,OGASAWARA M.Tunneling through an embankment using all ground fasten method[J].Tunneling and Underground Space Technology,2005,20(2):121-127.
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[5]中华人民共和国行业标准编写组.JTGF60-2009,公路隧道施工技术规范[S].北京:人民交通出版社,2009.(The Professional Standards Compilation Group of the People′s Republic of China.JTGF60-2009Technical specifications for road tunnel construction[S].Beijing:China Communications Press,2009.(in Chinese))
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[7]李超.浅埋暗挖隧道管棚作用机理及施工过程三维数值模拟[硕士学位论文][D].天津:天津大学,2010.(LI Chao.Mechanism of pipe-roof in shallow-buried tunnels and 3D numerical simulation of construction process[M.S.Thesis][D].Tianjin:Tianjin University,2010.(in Chinese))
[8]TAN W L,RANJITH P G.Numerical analysis of pipe roof reinforcement in soft ground tunnelling[C]//Proceedings of the 16th International Conference on Engineering Mechanics.Seattle,USA:ASCE,2003:1-10.
[9]NG C W W,LEE G T K.A three-dimensional parametric study of the use of soil nails for stabilizing tunnel faces[J].Computers and Geotechnics,2002,29(8):673-697.
[10]YOO C.Finite-element analysis of tunnel face reinforced by longitudinal pipes[J].Computers and Geotechnics,2002,29(1):73-94.
[11]邢厚俊,徐祯祥.大管棚在超浅埋暗挖大跨度隧道工程中的应用[J].岩石力学与工程学报,1999,18(增):1 059-1 061.(XING Houjun,XU Zhenxiang.Application of big pipe-roof in large-span shallow buried tunnel engineering[J].Chinese Journal of Rock Mechanics and Engineering,1999,18(Supp.):1 059-1 061.(in Chinese))
[12]常艄东.管棚法超前预支护作用机理的研究[博士学位论文][D].成都:西南交通大学,1999.(CHANG Shaodong.Research on prebrace mechanism of pipe umbrella method[Ph.D.Thesis][D].Chengdu:Southwest Jiaotong University,1999.(in Chinese))
[13]李健,谭忠盛,喻渝,等.浅埋下穿高速公路黄土隧道管棚变形监测及受力机制分析[J].岩石力学与工程学报,2011,30(增1):3 002-3 008.(LI Jian,TAN Zhongsheng,YU Yu,et al.Analysis of deformation monitoring and mechanical behaviors of big pipe-roof for shallow-buried large-span tunnel to underpass highway[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(Supp.1):3 002-3 008.(in Chinese))
[14]苟德明,阳军生,张戈.浅埋暗挖隧道管棚变形监测及受力机制分析[J].岩石力学与工程学报,2007,26(6):1 258-1 264.(GOUDeming,YANG Junsheng,ZHANG Ge.Deformation monitoring and mechanical behaviors of pipe-roof in shallow tunnels[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(6):1 258-1 264.(in Chinese))
[15]HISATAKE M,OHNO S.Effects of pipe roof supports and the excavation method on the displacements above a tunnel face[J].Tunnelling and Underground Space Technology,2008,23(2):120-127.
[16]郭璇,张鸿儒,蒙蛟,等.软弱围岩隧道管棚预支护开挖土压分布模型试验[J].岩石力学与工程学报,2016,35(6):1 214-1 224.(GUO Xuan,ZHANG Hongru,MENG Jiao,et al.Model test on soil pressure distribution in prestored excavation of soft surrounding rock tunnel tunnels[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(6):1 214-1 224.(in Chinese))
[17]李化云,张志强,王志杰,等.浅埋大跨隧道预加固措施相似模型试验研究[J].岩土力学,2012,33(增2):133-138.(LI Huayun,ZHANG Zhiqiang,WANG Zhijie,et al.Similarity model test study of pre-reinforcement measures of shallow tunnel with large crosssection[J].Rock and Soil Mechanics,2012,33(Supp.2):133-138.(in Chinese))
[18]徐芝纶.弹性力学[M].第五版.北京:高等教育出版社,2016:139-141.(XU Zhilun.Elasticity mechanics[M].4th ed.Beijing:Higher Education Press,2006:139-141.(in Chinese))
[19]杨端生,黄炎.双参数弹性地基上的正交异性矩形板的弯曲[J].工程力学,2009,26(3):26-30.(YANG Duansheng,HUANG Yan.Bending of orthotropic rectan-gular plated on double-parametric elastic foundation[J].Engineering Mechanics,2009,26(3):26-30.(in Chinese))
[20]李晓红,卢义玉,康勇,等.岩石力学实验模拟技术[M].北京:科学出版社,2007:3-16.(LI Xiaohong,LU Yiyu,KANG Yong,et al.Rock mechanics simulation technology[M].Beijing:Rock Mechanics and Engineering,2007:3-16.(in Chinese))
[21]汤华,熊晓荣,吴振君,等.隧道锚抗拔作用机理的室内模型试验[J].上海交通大学学报,2015,49(7):935-939.(TANG Hua,XIONG Xiaorong,WU Zhenjun,et al.Laboratory model test study of pullout mechanism of tunnel anchor[J].Journal of Shanghai Jiaotong University,2015,49(7):935-939.(in Chinese))
[2]MIWA M,OGASAWARA M.Tunneling through an embankment using all ground fasten method[J].Tunneling and Underground Space Technology,2005,20(2):121-127.
[3]王梦恕.地下工程浅埋暗挖技术通论[M].合肥:安微教育出版社,2004:12.(WANG Mengshu.Underground Engineering shallow boring technology[M].Hefei:An Micro Education Press,2004:12.(in Chinese))
[4]赵建平.浅埋暗挖隧道管棚预支护机理及其效用研究[硕士学位论文][D].长沙:中南大学,2005.(ZHAO Jianping.Shallow burial tunnel shed pipe shed support mechanism and effectiveness[M.S.Thesis][D].Changsha:Central South University,2005.(in Chinese))
[5]中华人民共和国行业标准编写组.JTGF60-2009,公路隧道施工技术规范[S].北京:人民交通出版社,2009.(The Professional Standards Compilation Group of the People′s Republic of China.JTGF60-2009Technical specifications for road tunnel construction[S].Beijing:China Communications Press,2009.(in Chinese))
[6]关宝树.隧道力学概论[M].成都:西南交通大学出版社,1993:3.(GUAN Baoshu.Introduction to tunnel mechanics[M].Chengdu:Southwest Jiaotong University Press,1993:3.(in Chinese))
[7]李超.浅埋暗挖隧道管棚作用机理及施工过程三维数值模拟[硕士学位论文][D].天津:天津大学,2010.(LI Chao.Mechanism of pipe-roof in shallow-buried tunnels and 3D numerical simulation of construction process[M.S.Thesis][D].Tianjin:Tianjin University,2010.(in Chinese))
[8]TAN W L,RANJITH P G.Numerical analysis of pipe roof reinforcement in soft ground tunnelling[C]//Proceedings of the 16th International Conference on Engineering Mechanics.Seattle,USA:ASCE,2003:1-10.
[9]NG C W W,LEE G T K.A three-dimensional parametric study of the use of soil nails for stabilizing tunnel faces[J].Computers and Geotechnics,2002,29(8):673-697.
[10]YOO C.Finite-element analysis of tunnel face reinforced by longitudinal pipes[J].Computers and Geotechnics,2002,29(1):73-94.
[11]邢厚俊,徐祯祥.大管棚在超浅埋暗挖大跨度隧道工程中的应用[J].岩石力学与工程学报,1999,18(增):1 059-1 061.(XING Houjun,XU Zhenxiang.Application of big pipe-roof in large-span shallow buried tunnel engineering[J].Chinese Journal of Rock Mechanics and Engineering,1999,18(Supp.):1 059-1 061.(in Chinese))
[12]常艄东.管棚法超前预支护作用机理的研究[博士学位论文][D].成都:西南交通大学,1999.(CHANG Shaodong.Research on prebrace mechanism of pipe umbrella method[Ph.D.Thesis][D].Chengdu:Southwest Jiaotong University,1999.(in Chinese))
[13]李健,谭忠盛,喻渝,等.浅埋下穿高速公路黄土隧道管棚变形监测及受力机制分析[J].岩石力学与工程学报,2011,30(增1):3 002-3 008.(LI Jian,TAN Zhongsheng,YU Yu,et al.Analysis of deformation monitoring and mechanical behaviors of big pipe-roof for shallow-buried large-span tunnel to underpass highway[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(Supp.1):3 002-3 008.(in Chinese))
[14]苟德明,阳军生,张戈.浅埋暗挖隧道管棚变形监测及受力机制分析[J].岩石力学与工程学报,2007,26(6):1 258-1 264.(GOUDeming,YANG Junsheng,ZHANG Ge.Deformation monitoring and mechanical behaviors of pipe-roof in shallow tunnels[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(6):1 258-1 264.(in Chinese))
[15]HISATAKE M,OHNO S.Effects of pipe roof supports and the excavation method on the displacements above a tunnel face[J].Tunnelling and Underground Space Technology,2008,23(2):120-127.
[16]郭璇,张鸿儒,蒙蛟,等.软弱围岩隧道管棚预支护开挖土压分布模型试验[J].岩石力学与工程学报,2016,35(6):1 214-1 224.(GUO Xuan,ZHANG Hongru,MENG Jiao,et al.Model test on soil pressure distribution in prestored excavation of soft surrounding rock tunnel tunnels[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(6):1 214-1 224.(in Chinese))
[17]李化云,张志强,王志杰,等.浅埋大跨隧道预加固措施相似模型试验研究[J].岩土力学,2012,33(增2):133-138.(LI Huayun,ZHANG Zhiqiang,WANG Zhijie,et al.Similarity model test study of pre-reinforcement measures of shallow tunnel with large crosssection[J].Rock and Soil Mechanics,2012,33(Supp.2):133-138.(in Chinese))
[18]徐芝纶.弹性力学[M].第五版.北京:高等教育出版社,2016:139-141.(XU Zhilun.Elasticity mechanics[M].4th ed.Beijing:Higher Education Press,2006:139-141.(in Chinese))
[19]杨端生,黄炎.双参数弹性地基上的正交异性矩形板的弯曲[J].工程力学,2009,26(3):26-30.(YANG Duansheng,HUANG Yan.Bending of orthotropic rectan-gular plated on double-parametric elastic foundation[J].Engineering Mechanics,2009,26(3):26-30.(in Chinese))
[20]李晓红,卢义玉,康勇,等.岩石力学实验模拟技术[M].北京:科学出版社,2007:3-16.(LI Xiaohong,LU Yiyu,KANG Yong,et al.Rock mechanics simulation technology[M].Beijing:Rock Mechanics and Engineering,2007:3-16.(in Chinese))
[21]汤华,熊晓荣,吴振君,等.隧道锚抗拔作用机理的室内模型试验[J].上海交通大学学报,2015,49(7):935-939.(TANG Hua,XIONG Xiaorong,WU Zhenjun,et al.Laboratory model test study of pullout mechanism of tunnel anchor[J].Journal of Shanghai Jiaotong University,2015,49(7):935-939.(in Chinese))