平行双孔隧道开挖变形三维数值分析

基于Gibson土建立平行双孔隧道的三维实体结构计算模型，考虑衬砌与周围土体的共同作用，并在盾构开挖面处施加表面力以模拟切削刀盘的推进力效应，分析平行双孔隧道同步开挖及不同滞后距离异步开挖时隧道相互作用所引起的周边土体变形及收敛形式。研究表明，平行双孔隧道异步开挖时，滞后距离对超前开挖隧道周围的竖直沉降影响微小，而对后挖隧道断面竖直沉降以及左右隧道水平位移的影响较大；随两隧道间距的增加，开挖时相互的影响会随之减小。

Numerical simulation on effects of different construction processes on behaviour of parallel twin tunnels

A 3D entity structure calculation model of parallel twin tunnels was constructed based on Gibson Soil to investigate the effects of different excavation procedures on the soil movements around the twin tunnels. Numerical simulation analysis was performed by using three dimensional finite ele- ment analysis. Shield tunnel construction was simulated considering shield excavation face supported by uniform distributed load. The interaction between lining and surrounding soil layers was taken in- to account. The soil layer displacements around the the twin tunnels and contraction due to simulta- neous excavating and different construction procedures were investigated. It shows that the distance between the excavating sites of the twin tunnels with different-step construction procedure has a small effect on the vertical displacement of the formerly excavated tunnel, whereas it has a higher effect on the sectional vertical settlement of the latterly excavated tunnel and the horizontal displacements be- tween the twin tunnels. The interaction between the twin tunnels is lessened with the increase of their space.