摘要
贵阳南垭路三号隧道为两座分离式的单跨四车道市政隧道,最大开挖跨度21.878 m,最大开挖面积为245.7 m^2,处于喀斯特地貌区,地下岩溶和岩石节理裂隙发育,围岩破碎且施工工期紧。基于以上施工背景,文章开展基于工期目标的软弱破碎围岩单跨四车道市政隧道施工优化研究。首先利用强度折减法对裸洞围岩稳定性进行定量评价,发现Ⅳ级围岩裸洞具有自稳条件,Ⅴ级围岩裸洞则不满足安全系数要求;在此基础上结合不同工法的施工模拟和工期推演,对施工方案进行优化,最终确定了南垭路三号隧道在Ⅳ级围岩地段采用三台阶五步法施工,Ⅴ级围岩地段采用双侧壁导坑法施工的方案;最后对洞身Ⅳ级、Ⅴ级围岩地段工法转换进行优化,将施工工期提前了9个月,创造了显著的经济和社会效益,研究成果可为今后类似工程的修建提供借鉴。
The No.3 tunnel on Nanya Road in Guiyang is a twin-tube independent single-span four-lane munici pal tunnel with the maximum excavation span of 21.878 m and the maximum excavation area of 245.7 m^2 as well as developed underground karst and joint fissure since it is located in karst area,the,and the rock mass is fractured and construction time is tight.A research on the construction optimization of single-span four-lane municipal tun nel in weak and fractured surrounding rocks is conducted based on the construction period target.The strength re duction method is used to quantitatively evaluate the surrounding rock stability of the unsupported cavern and it is found that the unsupported rock of grade IV has the conditions to reach self-stability but the unsupported rock mass of grade V doesn′t meet the requirement of safety factor;based on the construction simulation and construction peri od deduction of different construction methods,the construction scheme is optimized,and it is determined for the No.3 tunnel at Nanya Road to adopt three-bench five-step excavation method in the surrounding rock of gradeⅣand double side drift method for the rock mass of grade V;the switch of construction method for the main tunnel in rocks of gradeⅣandⅤis optimized,and the construction period is shortened by 9 months.
作者
杨志强
方晶
刘湘林
郑余朝
YANG Zhiqiang;FANG Jing;LIU Xianglin;ZHENG Yuchao(Beijing Constructioin Engineering Group,Beijing 100015;Key Laboratory of Transportation Tunnel Engineering,Ministry of Education,Chengdu 610031)
出处
《现代隧道技术》
EI
CSCD
北大核心
2020年第2期184-191,203,共9页
Modern Tunnelling Technology
关键词
单跨四车道隧道
围岩稳定性
强度折减法
数值模拟
工期目标
Single-span four-lane tunnel
Stability of surrounding rock
Strength reduction method
Numerical simulation
Target of construction period
