深厚软土盾构隧道施工地表沉降数值模拟计算

近些年越来越多的沿海城市兴建地铁,盾构隧道不可避免地会穿越软土地区,因而研究软土盾构施工引起的地表沉降规律变得尤为重要.以温州某盾构隧道为例,利用PLAXIS有限元软件,构建二维数值分析模型,分别研究单线隧道和双线隧道下的地表沉降规律.结果表明:土体变形逐步由隧道向上传递到地表,产生沉降,单线隧道最大地表沉降值为10.1 mm;单线隧道顶部管片的竖向变形最大达到2.56 mm,左侧腰部和右侧腰部管片往中间的变形量均为0.96 m m;盾构隧道埋深越大,则盾构施工引起的最大地表沉降量越小,而沉降槽宽度越大;在双线盾构施工完成后,后行隧道引起的地表沉降更大,同时发现双线隧道间距越小,两隧道之间的相互影响越大,由此造成了地表沉降量更大.

Numerical Simulation of Ground Settlement During Shield Construction in Deep Soft Soil

In recent years, more and more cities have built subways, and shield tunnels will inevitably pass through soft soil areas. Therefore, it is particularly important to study the surface settlement caused by soft soil shield tunneling. Taking a shield tunnel in Wenzhou as an example and using PLAXIS finite element software to establish a two-dimensional numerical analysis model, the surface settlement under single-tunnels and doble-tunnels are studies respectively. The results show that the soil deformation is gradually transferred upwards from the tunnel to the surface, further causing settlement. The maximum value of surface settlement in single-tunnels is 10.1 mm; The vertical deformation of the top segment is up to 2.56 mm, and the horizontal deformation of the left and right waist pipes is 0.96 mm both. After the completion of the double-tunnels, the surface settlement induced by back tunnel becomes larger. When the distance between the two tunnels increases, the mutual influence between the two tunnels becomes larger.