摘要
为深入分析采用复合式衬砌形式的大断面隧道初支与二衬的荷载形成机理及其二衬荷载分担比例,从而为大断面隧道衬砌结构设计提供参考意见,文中以深汕西改扩建项目城仔山隧道工程为例,运用FLAC3D软件建立不同埋深条件下大断面隧道施工计算模型,研究了Va级围岩大断面隧道在双侧壁导坑工法下的荷载分担情况。研究结果表明,大断面隧道二衬荷载分担比通常不超过50%,说明二衬并非主要承载结构。此外,大断面隧道二衬分担比与埋深的关联性不高,但二衬所承担的荷载大小与埋深有关,且埋深越大,初始荷载越高,二衬荷载分担比增长幅度也越明显。二衬在施工后参与荷载承担作用,承受的二衬荷载增长速度较快,并在支护结构稳定后其变化曲线趋于平稳。隧道拱顶竖向荷载均大于边墙横向荷载,且拱顶的二衬荷载分担比也更高。软弱围岩段大断面隧道宜加强初支刚度,以减小二衬分担的荷载。研究成果为大断面隧道支护优化设计提供了参考意见。
To better analyze the load formation mechanism of the primary and secondary linings in large-section tun-nels with composite linings and the load-sharing ratio of the secondary lining,and to provide reference for the design of large-section tunnel lining structures,this paper relies on the Chengzai mountain tunnel project of the Shenshanxi expansion project.Using FLAC3D,different construction calculation models of large-section tunnels under various burial depths were established to study the load-sharing situation of large-section tunnels with Va-grade surround-ing rock under the double-side wall guiding method.The results indicate that the load-sharing ratio of the secondary lining in large-section tunnels generally does not exceed 50%,indicating that the secondary lining is not the primary load-bearing structure.The correlation between the secondary lining load-sharing ratio and burial depth is low;how-ever,the magnitude of the load borne by the secondary lining is related to the burial depth.The deeper the burial,the higher the initial load,and the more significant the increase in the secondary lining load-sharing ratio.After its con-struction,the secondary lining starts to bear loads,with the load on the secondary lining increasing rapidly.After the support structure stabilizes,the load variation curve of the secondary lining tends to stabilize.The vertical load on the tunnel crown is generally greater than the transverse load on the sidewalls,and the load-sharing ratio of the second-ary lining at the crown is also generally higher.For large-section tunnels in weak surrounding rock segments,it is ad-visable to enhance the stiffness of the primary lining to reduce the load borne by the secondary lining.The findings provide reference for the optimization design of large-section tunnel support structures.
作者
竺宏杰
周建
庄一舟
陈良
ZHU Hongjie;ZHOU Jian;ZHUANG Yizhou;CHEN Liang(Zhejiang University of Technology College of Civil Engineering,Hangzhou 310023,China;Hangzhou City University College of Engineering,Hangzhou 310015,China)
出处
《低温建筑技术》
2024年第10期90-95,109,共7页
Low Temperature Architecture Technology
基金
浙江省交通厅计划项目(2021050)
浙江省教育厅一般项目(Y202351526)。
关键词
大断面隧道
数值模拟
二衬荷载分担比
二衬荷载
large cross-section tunnel
numerical simulation
load sharing ratio of secondary lining
secondary lining pressure
