考虑时空效应的浅埋软弱隧道预留变形量确定方法
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摘要
在浅埋软弱隧道台阶法施工中,预留变形量不仅要考虑围岩累计变形量,也要考虑支护结构随围岩变形的时空效应。基于围岩变形监测资料,对某隧道支护与围岩的协调变形过程进行了详细分析,发现隧道收敛与沉降变形具有明显的时空效应,在此基础上提出了理想预留变形量下的变形模型。在考虑台阶法施工中的围岩变形时空效应下,对隧道的预留变形量进行了监测,上台阶节段初支段落整体上移200mm;中台阶衬砌在设计轮廓线外移150mm,节段长度不变且对应钢架半径增大150mm;下台阶节段钢架对应半径做同样的增加,对接中台阶进行拼装施工。后期监测资料表明,隧道在完成变形后基本达到了设计轮廓线位置。该预留变形量的确定方法既有效避免了大变形对隧道的影响,也解决了支护结构施工与材料用料上的矛盾问题,为浅埋软弱地层隧道预留变形量确定提供了新的思路。
During construction of tunnel by staging method in shallow buried and soft stratum,the reserved deformation shall not only consider the cumulative deformation of surrounding rock,but also consider the time-space effect due to deformation of support structure along with the surrounding rocks.Based on the comprehensive monitoring data,the deformation process of tunnel support and surrounding rock are analyzed in the consideration of time-space effect.Judging from the settlement difference between the vault and the arch foot,it is considered that the deformation of the support is mainly composed of two parts:the lateral flexure and the overall subsidence.Considering time-space effect of surrounding rock deformation,the reserved deformation has been tried as:the excavation outline is raised 200 mm in the first bench;the excavation outline is deviated 150 mm in the middle bench and the radius of steel frame in this segment is increased a length of 150 mm;the steel frame in the third bench is dealt with the same way and installed with the last segment.The monitoring data in later phase show that the primary support just reaches the designed position after deformation.This method for reserved deformation method is not only effective to avoid the influence of large deformation,but also can solve the problem of supporting position and materials,providing a new concept of determining the reserved deformation in shallow tunnel.
During construction of tunnel by staging method in shallow buried and soft stratum,the reserved deformation shall not only consider the cumulative deformation of surrounding rock,but also consider the time-space effect due to deformation of support structure along with the surrounding rocks.Based on the comprehensive monitoring data,the deformation process of tunnel support and surrounding rock are analyzed in the consideration of time-space effect.Judging from the settlement difference between the vault and the arch foot,it is considered that the deformation of the support is mainly composed of two parts:the lateral flexure and the overall subsidence.Considering time-space effect of surrounding rock deformation,the reserved deformation has been tried as:the excavation outline is raised 200 mm in the first bench;the excavation outline is deviated 150 mm in the middle bench and the radius of steel frame in this segment is increased a length of 150 mm;the steel frame in the third bench is dealt with the same way and installed with the last segment.The monitoring data in later phase show that the primary support just reaches the designed position after deformation.This method for reserved deformation method is not only effective to avoid the influence of large deformation,but also can solve the problem of supporting position and materials,providing a new concept of determining the reserved deformation in shallow tunnel.
引文
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[2]赵东平,喻渝,王明年,等.大断面黄土隧道变形规律及预留变形量研究[J].现代隧道技术,2009,46(6):64-69.
[3]吕勤,张顶立,黄俊.城市地铁暗挖施工地层变形机理及控制实践[J].中国安全科学学报,2003,13(7):29-34.
[4]戴仕敏.城市超软弱地层中浅埋隧道变形特征与实测分析[J].地下空间与工程学报,2015,11(S2).
[5]赖金星,樊浩博,来弘鹏,等.软弱黄土隧道变形规律现场测试与分析[J].岩土力学,2015,36(7):2003-2012.
[6]JTG D70—2010公路隧道设计细则[S].
[7]TB 10003—2005铁路隧道设计规范[S].
[8]王梦恕.隧道工程浅埋暗挖法施工要点[J].隧道建设,2006,26(5):1-4.
[9]王梦恕.地下工程浅埋暗挖技术通论[M].合肥:安徽教育出版社,2004.
[10]赵勇.隧道围岩动态变形规律及控制技术研究[J].北京交通大学学报,2010,34(4):1-5.
[11]赵勇.隧道软弱围岩变形机制与控制技术研究[D].北京:北京交通大学,2012.
[12]营磊,盖英志.软弱围岩大断面海底隧道预留变形量设置及对钢拱架影响的探讨[J].隧道建设,2008,8(3):285-289.
[13]关宝树.软弱围岩隧道变形及其控制技术[J].隧道建设,2011,31(1):1-17.
[14]陈建勋,王梦恕,轩俊杰,等.两车道公路黄土隧道变形规律[J].交通运输工程学报,2012,12(3):13-22.
[15]梁巍,黄明利.大跨度隧道CRD法穿越含水软弱层沉降变形控制[J].岩石力学与工程学报,2007,(s2):3738-3742.
[16]岳向红,杨永波,李祺,等.松软地层浅埋暗挖公路隧道现场监测分析研究[J].岩土力学,2010,31(s1):337-341.
[17]关宝树.隧道施工要点集[M].北京:人民交通出版社,2011.
[18]中国有色金属工业西安勘察设计研究院.福州市湖东东路隧道监测报告[R].2016.
[19]汪珂,赖金星,邱军领,等.强风化花岗岩隧道水平旋喷桩预加固效果分析[J].现代隧道技术,2016,53(5):168-175.
[20]覃维,隧道支护侵限机理分析及换拱方案优化研究[D].西安:长安大学,2013.
[21]段慧玲,张林.大跨度公路隧道合理开挖方法对比研究[J].土木工程学报,2009,(9):114-119.
[22]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,2012,31(s1):2729-2737.