浅埋偏压隧道进洞施工力学特性研究
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摘要
隧道进口段围岩常常具有浅埋、偏压、风化严重等特点,若施工处理不当,极易造成洞口边、仰坡滑动和洞内塌方等事故,从而影响隧道正常施工和人员安全。结合具体工程,对浅埋偏压隧道进洞施工开展了三维数值模拟,并结合监测数据分析了施工对围岩和支护结构力学特性的影响,主要结论如下:围岩变形具有非对称性,浅埋侧围岩变形量要小于深埋侧;随着隧道的逐步开挖,隧道深埋侧拱脚和浅埋侧拱肩处围岩易于发生剪切破坏,而且围岩的塑性区也主要位于这两个区域,并逐渐向拱顶上方贯通;初期支护结构的受力状态受偏压地形影响显著呈非对称性,而超前支护受偏压影响较小;现场实测围岩变形与计算结果较为吻合,且变形在22天后达到稳定状态。
The surrounding rock at tunnel entrance mostly has the characteristics of shallow,unsymmetrically loaded and serious weathering,etc. If improper construction measures are taken,it may trigger accidents of slope slide at tunnel entrance and collapse at tunnel face,which further affects the normal tunnel construction and the personnel safety. Three-dimensional numerical simulation was carried out to analyze the construction of a shallow tunnel entrance under unsymmetrically pressure. By comparing and analyzing the calculation results and the in-situ monitoring data,the construction mechanical properties of surrounding rock and support structure were revealed,and conclusions were drawn as following. Firstly,the deformation of the surrounding rock is asymmetric at the tunnel face,i.e. the deformation at the shallow is smaller than that at the deep side. Secondly,with the gradual tunnel excavation,the surrounding rock at the foot of deep side and the arch of shallow side is easy to be shear failure,what is more,the plastic zones of surrounding rock are mainly located at these two places,and it will gradually intercommunicate towards the tunnel arch. Thirdly,the stress state of the initial support structure is significantly affected by the unsymmetrically terrain,while the advance support structure is hardly affected by the asymmetric pressure. The in-situ measured deformation values of surrounding rock agree well with the calculation results,and the deformation will reach a steady state after 22 days.
The surrounding rock at tunnel entrance mostly has the characteristics of shallow,unsymmetrically loaded and serious weathering,etc. If improper construction measures are taken,it may trigger accidents of slope slide at tunnel entrance and collapse at tunnel face,which further affects the normal tunnel construction and the personnel safety. Three-dimensional numerical simulation was carried out to analyze the construction of a shallow tunnel entrance under unsymmetrically pressure. By comparing and analyzing the calculation results and the in-situ monitoring data,the construction mechanical properties of surrounding rock and support structure were revealed,and conclusions were drawn as following. Firstly,the deformation of the surrounding rock is asymmetric at the tunnel face,i.e. the deformation at the shallow is smaller than that at the deep side. Secondly,with the gradual tunnel excavation,the surrounding rock at the foot of deep side and the arch of shallow side is easy to be shear failure,what is more,the plastic zones of surrounding rock are mainly located at these two places,and it will gradually intercommunicate towards the tunnel arch. Thirdly,the stress state of the initial support structure is significantly affected by the unsymmetrically terrain,while the advance support structure is hardly affected by the asymmetric pressure. The in-situ measured deformation values of surrounding rock agree well with the calculation results,and the deformation will reach a steady state after 22 days.
引文
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[8]李皓晖,虞晓卫,张旺兴,等.岩隧道衬砌开裂机理分析及预防措施[J].施工技术,2014,43(18):74-76.(Li Haohui,Yu Xiaowei,Zhang Wangxing,et al.Mechanism analysis and prevention measures about soft rock tunnel lining cracking[J].Construction Technology,2014,43(18):74-76.(in Chinese))
[9]Liu W B,Liu B G,Wang W F.Pipe shield effect analysis of double-arched tunnel under unsymmetrical pressures[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(Supp.2):3704-3710.
[10]Lei M F,Peng L M,Shi C H.Model test to investigate the failure mechanisms and lining stress characteristics of shallow buried tunnels under unsymmetrical loading[J].Tunnelling and Underground Space Technology,2015,46:64-75.
[2]高广运,杨长,冯世进,等.浅埋偏压隧道动态施工模拟工程实例[J].现代隧道技术,2006,43(增):393-396.(Gao Guangyun,Yang Chang,Feng Shijin,et al.Research on dynamic simulation of shallow bias tunnel.modern tunneling technology[J].Modern Tunneling Technology,2006,43(Supp.):393-396.(in Chinese))
[3]高文学,孙文龙,周文旭,等.浅埋偏压隧道开挖数值模拟与监测分析[J].施工技术,2011,40(3):48-50.(Gao Wenxue,Sun Wen Long,Zhou Wenxu,et al.Numerical simulation and monitoring analysis for construction process of shallow tunnel under unsymmetrical pressure[J].Construction Technology,2011,40(3):48-50.(in Chinese))
[4]李志星,张宇华,石效民.浅埋偏压隧道开挖技术[J].施工技术,2011,40(3):60-62.(Li Zhixing,Zhang Yuhua,Shi Xiaomin.Excavation technology of shallow tunnel under unsymmetrical pressure[J].Construction Technology,2011,40(3):60-62.(in Chinese))
[5]刘玉清,蒋俊峰,邵大鹏,等.新寨隧道进口浅埋偏压隧道施工技术[J].现代隧道技术,2011,48(2):87-93.(Liu Yuqing,Jiang Junfeng,Shao Dapeng,et al.Construction techniques of shallow and unevenpressured xinzhai tunnel entrance[J].Modern Tunneling Technology,2011,48(2):87-93.(in Chinese))
[6]高天羽,罗志刚.隧道浅埋偏压洞口段施工技术[J].公路,2012,7(7):311-314.(Gao Tian Yu,Luo Zhi Gang.Construction technology of shallow bias tunnel[J].Highway,2012,7(7):311-314.(in Chinese))
[7]郭亮,李俊才,张志铖,等.地质雷达探测偏压隧道围岩松动圈的研究与应用[J].岩石力学与工程学报,2011,30(增1):3009-3015.(Guo Liang,Li Juncai,Zhang Zhicheng,et al.Research of surrounding rock loose zone of tunnel under unsymmetrical loading with ground penetrating radar and its application[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(Supp.1):3009-3015.(in Chinese))
[8]李皓晖,虞晓卫,张旺兴,等.岩隧道衬砌开裂机理分析及预防措施[J].施工技术,2014,43(18):74-76.(Li Haohui,Yu Xiaowei,Zhang Wangxing,et al.Mechanism analysis and prevention measures about soft rock tunnel lining cracking[J].Construction Technology,2014,43(18):74-76.(in Chinese))
[9]Liu W B,Liu B G,Wang W F.Pipe shield effect analysis of double-arched tunnel under unsymmetrical pressures[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(Supp.2):3704-3710.
[10]Lei M F,Peng L M,Shi C H.Model test to investigate the failure mechanisms and lining stress characteristics of shallow buried tunnels under unsymmetrical loading[J].Tunnelling and Underground Space Technology,2015,46:64-75.
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