黄土地区基坑开挖对下卧变截面地铁隧道影响数值分析

Numerical Analysis of Influence of Deep Excavations on Underlying Subway Tunnels with Different Section

为预先了解黄土地区深基坑开挖工程对下卧变截面地铁隧道的影响,以现场地层及地铁隧道相关参数为依据,采用FLAC^(3D)对施工及降水过程进行了数值模拟计算。结果表明:地下水位的变化引起土体应力的改变,进而会对隧道变形产生影响;开挖卸荷引起坑底回弹,导致整体隧道发生向上隆起,基坑开挖范围内马蹄形隧道隆起量相对较小;另外,盾构隧道和马蹄形隧道的接头部位位于隆起最大区域,施工期间应加强这一区域变形监测,需要密切关注结构防水措施的破坏。

In order to understand the influence of Xi’an East Gate Plaza deep excavation engineering to underlying subway tunnel with variable cross-section, this paper adopted FLAC3 D to analysis the influence of the deep excavation to underlying subway tunnel with variable cross-section, based on the stratum information and subway tunnel parameters. The results show that the change in the groundwater level causes a change in the stress of the soil, which in turn affects the deformation of the tunnel. The bottom rebound caused by excavation unloading, which lead to tunnel upward bulge. The amount of horseshoe-shaped tunnel structure upward bulge is relatively slow, the relative risk ratio of shield tunnel is bigger than horseshoe-shaped tunnel. In addition, joints of shield tunnel and horseshoe-shaped tunnel located in the maximum uplift area, which need to be payed close attention to the destruction of waterproofing measures structure during excavation construction.