斜交小净距特大跨度隧道开挖围岩稳定性研究  

Stability Analysis of Surrounding Rock in Excavation of Small Spacing Skew Crossing Super-Large Span Tunnel

作　　者：李小飞 LI Xiaofei(China Railway 24th Bureau Group Co.Ltd.,Shanghai 200433,China)

机构地区：[1]中铁二十四局集团有限公司,上海200433

出　　处：《铁道建筑技术》2025年第4期176-180,共5页Railway Construction Technology

基　　金：中铁二十四局集团有限公司科技研发项目(科研2024-12)。

摘　　要：小净距斜交上跨沪昆线大庆山隧道是新建渝昆线控制性节点。采用强度折减极限分析法、现场监测法,开展三台阶六导洞法和三台阶法两种机械掘进方法下的小净距斜交上跨隧道施工期隧道围岩稳定性研究。结果表明:Ⅴ级围岩的大庆山隧道采用三台阶六导洞法使既有隧道与新建隧道中夹岩体出现刚度缓变,较好地平衡了围岩应力释放与初期支护强度关系,隧道围岩稳定性较高,安全系数达到1.64~1.67,较三台阶法的围岩稳定安全系数提高15%~20%;上台阶初期支护后围岩稳定时间接近于普通隧道拱顶沉降稳定时间平均值和水平位移收敛稳定时间平均值;中夹岩体厚度为1 B时,隧道围岩稳定时间为5~15 d;掌子面距离监测位置1~2.5 B范围时,84.62%的监测点围岩趋于稳定。The Daqing Mountain Tunnel,with a skewed crossing over the Shanghai-Kunming Railway at small clearance,is the control node of newly-built Chongqing-Kunming Railway.The strength reduction limit analysis method and on-site monitoring method were adopted to conduct the stability analysis of tunnel surrounding rock during construction of small clearance skew crossing tunnels under two mechanical boring methods:the three-step six-guideway method(TSSM)and the three-step method(TSM).The study shows that:the TSSM for Daqing Mountain Tunnel with V class surrounding rock makes the stiffness of the sandwiched rock body in the existing and new tunnels slow down,and better balances the relationship between the surrounding rock stress release and the strength of the initial support,so that the stability of surrounding rock is higher,and the coefficient of safety reaches 1.64-1.67,which is about 15%-20%higher than that of the TSM rock stability and safety coefficient.The stabilization time of the surrounding rock after the excavation of the upper step and the initial support is close to the average value of the stabilization time of the settlement of the arch and the stabilization time of the convergence of the horizontal displacements of an ordinary tunnel;when the thickness of the rock body between tunnels is 1 B,the stabilization time of the tunnel surrounding rock is 5-15 days;when the excavation surface is in the range of 1-2.5 B from the monitoring position,84.62%of the monitoring points of the surrounding rock tend to be stable.

关 键 词：高铁隧道 小净距 斜交上跨 围岩稳定 稳定安全系数 

分 类 号：U459.1[建筑科学—桥梁与隧道工程] U451.2[交通运输工程—道路与铁道工程]