粉砂土地区典型基坑开挖对周边土层位移场的影响

城市建设的快速发展,不可避免的出现大量近接工程,例如在既有运营地铁隧道周边、或既有道路、建筑周边出现基坑开挖工程。基坑开挖对周边环境的影响受到越来越多的关注,基坑开挖卸载对周不同的构筑物产生变形影响,超过相应控制要求,就会对构筑物的正常使用及安全产生不利影响。文中在Plaxis有限元软件平台上,基于土体小应变本构模型(HSS)分析典型类型基坑围护结构变形对周围土层的位移场的数值模拟分析。结果表明,坑外土体变形影响区可简化为规则的几何形状,在围护结构最大变形值相同的情况下,就变形值来说,踢脚变形最大,复合变形和内凸变形次之,悬臂变形最小;就影响范围来说,悬臂变形最大,复合变形和内凸变形次之,踢脚变形最小。

INFLUENCE OF SURROUNDING SOIL DISPLACEMENT FIELD UNDER EXCAVATION OF TYPICAL FOUNDATION PIT IN SILTY SOIL AREA

With the rapid development of urban construction, it inevitably leads to a large number of project-by proximity such as the excavation of the foundation pit around the existing subway tunnels, existing roads and buildings. The influence of excavation of foundation pit on the surrounding environment is attracting more attention as the unloading of foundation pit causes deformation of different structures around the foundation pit. If the deformation exceeds the corresponding control criterion, it will adversely affect the normal use and safety of the structure. On the Plaxis finite element software platform, the numerical simulation of the displacement field around the surrounding soil of typical types of foundation pit retaining structures was analyzed based on hardening soil model with small strain stiffness (HSS). The results show that the deformation area of the soil outside the pit can be simplified to regular geometry. When the maximum deformation value of the retaining structure is the same, the deformation values of the cantilever type, the skirting type, the compound type and the inner convex type decreased successively. On the contrary, the scope of influence was the opposite.