连拱隧道无中导洞施工技术与监测分析

Construction Technology without Middle Drift and Monitoring Analysis of Double-arch Tunnel

以云南省武易高速白龙坡隧道为工程实例,详细阐述了连拱隧道无中导洞施工的施工工艺和监测方法,对连拱隧道无中导洞施工过程中的技术难点进行分析,给出中隔墙的施工工艺和先行洞结构的保护方法。现场实测表明:(1)无中导洞施工方法是可行的,尽管其在洞口段对围岩变形控制能力较弱,但其施工工序简单,施工工期较短;(2)隧道变形特征具有明显的时空效应,而且围岩质量越好,变形值越小,稳定时间也越短;(3)后行洞的偏压效应十分明显,设计和施工时应对此有充分的考虑;(4)中隔墙是两个隧道的连接核心,所以中隔墙必须要有足够的强度与刚度,保证中墙稳定,是建成双连拱隧道的关键和基础。

Based on the project example of Bailongpo tunnel of Wuyi expressway in Yunnan,the construction technology without middle drift and monitoring method of double-arch tunnel are described.The main technical difficulties in the construction are analyzed in detail,and the construction technology process of mid-partition and protection method of structure of existing tunnel are given.The field monitoring results show that:(1)The construction technology without middle drift is feasible.Although its ability of controlling the deformation of surrounding rock is weak at the entrance of the cave,its construction procedure is simple and its construction period is short.(2)The deformation characteristics of tunnel have obvious space-time effect,and the better the quality of surrounding rock,the smaller the deformation value and the shorter the stability time.(3)The bias effect of the following tunnel is very obvious.We should give full consideration to the design and construction.(4)The middle partition wall is the core of the two tunnels,so the middle wall must have enough strength and stiffness to ensure the stability.It is the key and foundation for the construction of a double-arch tunnel.