深基坑开挖对周边地表沉降变形的影响

Effect of excavation on sedimentation deformation of surrounding ground surface in deep foundation pit

为有效控制基坑周边地表的沉降变形,应用弹塑性大变形理论与有限差分理论,对哈尔滨地区桩-锚支护形式下深基坑开挖引起的周边地表沉降进行了数值模拟,分析了开挖深度、锚杆层数、建筑物距离对基坑周边地表沉降变形的影响规律及基坑周边地表沉降变形的量化范围。结果表明,基坑周边地表的沉降量与沉降范围随锚杆层数的增加而减小;建筑物的存在不仅增大了地表的沉降量,而且使基坑周围地表的最大沉降区向基坑方向移动;当建筑物与基坑的距离小于1.0倍基坑设计开挖深度时,建筑物距离对地表沉降变形的影响较明显;基坑开挖对周边地表的影响范围基本在与基坑边缘相距1.5倍基坑设计开挖深度范围之内。

Aimed at effectively controlling the sedimentation deformation of ground surface surrounding foundation pit, this paper introduces the application of elastic-plasticity large deformation theory and finite difference theory to model the sedimentation deformation of surrounding ground surface created by excavation of foundation pit supported with pile-anchor in Harbin, and analyze the rules of sedimentation deformation of ground surface nearby foundation pit affected by excavation depth, anchor layer, building space and quantified rang of sedimentation deformation of surrounding ground surface. The results demonstrate that the sedimentation deformation and sedimentation range of ground surface surrounding foundation pit decrease with increase of soil anchor layer, the building not only increases sedimentation deformation of ground surface but also makes the maximum sedimentation zone move to the foundation pit, the effect of distance between building and foundation pit on sedimentation deformation of ground surface is obvious when it is smaller than 1.0 times of design excavation depth of foundation pit, and the effect rang of excavation on surrounding ground surface is within 1.5 times of design excavation depth from foundation pit basically.