文章依托浏阳河隧道工程2号深大竖井施工实例,结合工程地质情况及施工中遇到的问题,提出了竖井施工技术及竖井转正洞的施工方案,即竖井采用明挖逆筑法施工,围护桩及喷锚支护与衬砌共同构成刚度较大的封闭式环状水平受力结构,竖井转正洞与竖井落底同步进行的施工方法,有利地解决了正洞开挖存在作业平台过高的问题.文章针对具体的施工过程建立了仿真模型,结合现场监测情况,分析了该施工方法的安全性.实施效果表明:地层位移、竖井的初期支护、竖井的二次衬砌、隧道正洞的初期支护受力均满足安全要求.竖井转正洞施工过程中,隧道正洞初期支护的较大弯矩集中在拱脚附近,最大弯矩随着开挖而增大.
Considering the geological conditions and problems encountered in construction,the vertical shaft con-struction technique and construction program for vertical shaft shifting to the main tunnel are proposed based on the No.2 shaft of the Liuyang river tunnel,for which the top-down construction method is adopted for the vertical shaft;an enclosed circular horizontal force-bearing structure with great stiffness is formed by the retaining piles, shot-crete-bolt support and lining;and the construction of the vertical shaft shifting to the main tunnel and the vertical shaft construction at the bottom are performed simultaneously,solving the problem of a high operating platform during main tunnel excavation. A simulation model is established, and the safety of this construction method is analyzed considering the onsite monitoring results. Implementation result shows that the ground displacement, the force on initial support and secondary lining of the vertical shaft and the force on the initial support of the main tunnel meet the safety requirements,and the large bending moments of the initial support of the main tunnel are mainly concen-trated near the tunnel arch spring during the construction of the vertical shaft shifting to the main tunnel,with the maximum bending moment increasing with excavation.