无中导连拱隧道施工掌子面纵向合理间距研究

Reasonable Distance Between Excavation Faces of Double Arch Tunnel without Middle Wall

基于单洞工法施工的无中导连拱隧道后行洞施工紧邻先行洞,后行洞和先行洞施工时掌子面的纵向间距对围岩变形及支护结构受力的影响不可忽视。以云南省某隧道为工程依托,建立三维弹塑性模型采用数值计算方法开展了连拱隧道动态施工的仿真研究,对连拱隧道开挖中监测断面拱顶沉降以及支护结构受力的空间影响效应、左右洞的相互影响效应进行分析。为避免施工中两洞影响区域的叠加,从先行洞拱顶沉降变化得出合理间距不小于32 m(约2.5D),根据支护结构受力得出合理间距不小于28 m(约2.2D)。综合来看,两开挖面的合理间距应控制在32 m(约2.5D)左右。

Based on the single-hole construction method in which the construction method of the second tunnel of a double-arch tunnel without middle wall is adjacent to the first tunnel. The distance between the excavation faces on the influence of the deformation of surrounding rock and supporting structure cannot be ignored. A tunnel in Yunnan Province was taken as an example in this paper,and a three-dimensional elastoplastic model is developed to carry out multi-arch tunnel dynamic construction simulation research. The space influence effect,mutual influence effect between the two tunnels of the vault subsidence and supporting structure force during construction were analyzed. In order to avoid the superposition of the affected areas of the two holes during construction,from the change in the settlement of the arch top of the advance tunnel,the reasonable distance should not be less than 32 m( about 2. 5 D),and the reasonable distance is not less than 28 m( about 2. 2 D) according to the force of the supporting structure. In general,the reasonable distance between two excavation faces should be controlled at about 32 m( about 2. 5 D).