公路双连拱隧道"三导洞法"施工的力学分析

应用有限元数值方法,对连拱隧道“三导洞法”施工时围岩和结构的受力、变形规律进行了分析.在两正洞拱部施工的时候,左右洞拱顶沉降约占最终沉降的70%.中墙受到偏载作用,不仅产生整体偏转,而且在偏转的同时产生扭转,引起墙体中部向左侧凸出的弯曲变形.二次衬砌分先后洞全断面一次浇筑时,围岩的底板隆起和拱顶沉降减小,边墙水平收敛增大,围岩稳定性增强.因此,在双连拱隧道设计与施工中,超前隧道初期支护尤其中墙顶拱脚处应予以加强;后进隧道一侧的中隔墙底部必须回填;中隔墙底部要设计足够的抗拉钢筋.

Mechanical analysis on construction process of highway double-arch tunnel with 3-heading excavation method

The regularity of stress and strain of surrounding rock and support structure when using(3-heading) excavation method to construct double-arc tunnel is carried out by FEM numerical method.The settlement of the two tunnels' arc crown occurs during the construction of arc part covers 70% of the final settlement.Bearing uneven load,the mid-partition not only deflects as a whole,but also twists at the same time,which makes the middle part of it bulges to the left.When the secondary lining of the lead tunnel is pouring full-face and the latter tunnel's follows,the bottom leave and the settlement of arc crown decrease,the horizontal convergence increases and the stability of surrounding rock is intensified.The initial support of the lead tunnel,especially the part on the top of mid-partition,should be strengthened,the foot of the latter tunnel at the side of the mid-partition must be backfilled,and the bottom of the mid-partition must have enough reinforcing steel bar during the design and construction process of double-arc tunnel.4 tabs,10 figs,6 refs.