粉煤灰堆积体大断面连拱隧道失稳破坏模式及施工力学研究  

Instability failure modes and construction mechanics of large-section multi-arch tunnels in fly ash deposits

作　　者：余涛[1] 廖杭 朱宁波 姚志刚[1] 方勇[1] 李希文[2] 田青峰 YU Tao;LIAO Hang;ZHU Ningbo;YAO Zhigang;FANG Yong;LI Xiwen;TIAN Qingfeng(Key Laboratory of Transportation Tunnel Engineering of Ministry of Education,Southwest Jiaotong University,Chengdu 610031,China;Sichuan Road and Bridge Highway Bridge Construction Group Co.,Ltd.,Chengdu 610093,China;China Railway Siyuan Survey and Design Group Co.,Ltd.,Wuhan 430063,China)

机构地区：[1]西南交通大学交通隧道工程教育部重点实验室,四川成都610031 [2]四川公路桥梁建设集团有限公司,四川成都610093 [3]中铁第四勘察设计院集团有限公司,湖北武汉430063

出　　处：《岩土工程学报》2024年第9期1909-1918,共10页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(52078428);四川公路桥梁集团有限公司科技计划项目(YBYPB-QT-025);四川省自然科学基金创新研究群体项目(2024NSFTD0013)。

摘　　要：国内目前并无在粉煤灰堆积体中采用暗挖法修建大断面连拱隧道的先例,给隧道的设计和施工带来了巨大挑战。依托盐坪坝隧道工程,开展了室内相似模型试验,探讨了该地层下大断面连拱隧道塌落拱演化规律及开挖施工力学行为。研究结果表明:连拱隧道在粉煤灰堆积体中开挖极易发生失稳,将失稳过程划分为4个演化阶段,破坏模式具有突发性、剧烈性、对称性、同步性特征;塌落拱高度约为隧道开挖跨度的40%。采用单侧壁导坑法开挖时粉煤灰堆积体承载力严重不足,根据相似换算关系左、右洞拱顶沉降分别为16.86,14.91cm,需对地层实施注浆加固;地层沉降呈对称“双峰状”,先行洞相较于后行洞受开挖影响较大,中隔墙的承载作用能够有效降低地层位移,单洞压力拱向双洞压力拱转换过程中,中隔墙受到偏压作用容易向先行洞侧偏转,建议在先行洞开挖时中隔墙添加支撑物。At present,there is no precedent of using the undermining method to construct large-section multi-arch tunnels in fly ash deposits in China,which brings great challenges to the design and construction of the tunnels.Based on the Yanpingba tunnel project,the laboratory similar model tests are carried out to explore the evolution laws of collapse arch and mechanical behaviors of excavation of the double-arch tunnel in fly ash stratum.The results show that the excavation of the multi-arch arch tunnels in the fly ash deposits is highly susceptible to instability,and the failure process is characterized by suddenness,intensity,symmetry and synchronicity.The height of the collapsed arch is about 0.4 times the excavation span of the tunnels.The bearing capacity of the fly ash deposits is seriously insufficient by using the single-side drift method,and the settlements of the left and right vaults are 16.86 cm and 14.91 cm according to the similarity relationship.It is necessary to implement grouting reinforcement for the stratum.The bearing effect of the partition wall can effectively reduce the displacement of the stratum,the shape of stratum settlement is‘bimodal’,and the first-excavated tunnel is more affected by excavation than the following one.During the process of conversion from single-tunnel pressure arch to double-tunnel one,the partition wall is easily deflected to the side of the first-excavated tunnel under the action of bias pressure,so it is suggested to add supports to the partition wall in the first-excavated of the existing tunnel.

关 键 词：连拱隧道 粉煤灰堆积体 模型试验 塌落拱 单侧壁导坑法 

分 类 号：TU45[建筑科学—岩土工程]