软土地区深基坑开挖坑底隆起的有限元分析
Finite element method analysis of bottom upheaval of deep foundation pits in soft-clay ground due to excavation
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摘要: 软土地区深基坑施工,会涉及到降低地下水的问题。传统深基坑设计常用弹性抗力法在计算基坑回弹变形,并未考虑降水的影响。本文在考虑渗流固结耦合的基础上,应用有限元软件ABAQUS建立存在工程桩和不存在工程桩的开挖与降水开挖三维基坑模型。通过对比分析,总结出基坑开挖降水过程中基坑坑底隆起的基本规律,分析深基坑坑底隆起变形及其影响因素,得出工程降水对深基坑土体的压密作用、基坑出现塑性隆起现象以及降水对基坑稳定有利的结论,并得出软土深基坑开挖过程中工程桩对坑底隆起变形有明显的抑制作用的结论。Abstract: The construction of deep foundation pits in soft-clay ground relates to dewatering problem. In the traditional design, the elastic resistance method is commonly used to calculate their rebound deformation without considering the effect of dewatering. A three-dimensional finite element model is established to simulate the excavation processes of deep foundation pits with or without considering engineering piles on the basis of seepage consolidation coupling by means of ABAQUS. Through comparison and analysis, the basic upheaval rules of pit bottom are summarized. The influencing factors for the bottom upheaval of deep foundation pits are analyzed. The conclusions are drawn as follows: the soils are compacted during dewatering; the foundation pit exhibits plastic upheaval; the dewatering is in favor of the stability of the foundation pits; the engineering piles in the foundation pit in soft-clay ground play an obvious role in inhibiting its bottom upheaval.