超大直径盾构施工对上覆隧道的影响分析

随着隧道工程的发展,隧道交叉穿越的情况越来越多,隧道的规模亦越来越大,如何减少隧道穿越施工对已建隧道的影响亦成为目前研究的重点之一。本文以上海沿江通道盾构施工下穿轨道交通3号线节点为研究对象,采用Midas/GTS软件建立三维弹塑性模型,通过激活钝化不同单元模拟盾构施工,分析对轨道交通3号线的影响。分析发现,超大直径盾构施工开挖卸除的土方量大,将引起较大的土体上抬,位移量已大大超过地层损失产生的地面沉降,使得隧道斜向上约45°角所包含的梯形范围内的土体(包含地铁结构)发生上抬现象。为确保3号线的位移最小,合理确定压重值,对不同的压重值进行参数分析,并进行工程类比,表明最佳值约为50 kPa。

Influence Analysis on the Upper Tunnel Affected by the Super-Large Shield Tunneling underneath

With the development of tunnel engineering,tunnel crossing construction becomes more frequently, and the diameter of the tunnel becomes larger, as a result, reducing the influence of the shielding construction to the existing tunnel is one of the most important areas to be studied. In this paper, a three-dimensional elastic-plastic model is built using Midas/GTS to analyze the influence of a super-large shield tunnel crossing through the Metro line 3 in Shanghai, by activating or killing the elements to model the construction process. The results show that the soil and the Metro line 3 above the shield move up with the tunneling for that the uplifting displacement caused by soil excavation, which is much more large than that caused by the “soil lose”. Consequently, the soil mass on the shield round up with 45° runs up.Weighting is effectively to reduce the displacement of the soil and the parameter analysis shows that 50kPa is appropriate in this project.