流固耦合对基坑开挖变形性状的影响研究

通过ABAQUS有限元模拟软件分别建立了考虑渗流影响和不考虑渗流影响的基坑开挖非稳定渗流有限元模型,采用修正剑桥模型并考虑支护桩与土体的接触作用,研究了支护结构侧向变形、坑外地表变形以及坑底隆起量随着基坑开挖的变化规律。然后将两个模型的支护桩及基坑变形性状进行对比,发现渗流—应力耦合作用下的基坑变形大于非耦合情况下的变形,说明考虑渗流应力耦合的数值模拟方法能够较好地模拟基坑降水引起的支护结构及基坑土体变形特征。最后,为控制基坑变形和保护周围环境,在考虑渗流—应力耦合作用的基础上又研究了预留反压土对支护结构的作用及对基坑变形的影响,结果表明,基坑内侧预留反压土堤可有效降低基坑及支护结构的变形。

Influence study on foundation pit deformation by seepage-stress coupled method

Two finite element models of foundation pit considering unsteady seepage or not with ABAQUS software are built respectively based on modified Cambridge model and taking the contact action between the soldier piles and the soil into consideration to study the lateral deformation of supporting structure, the surface deformation outside the pit and the upheaval of pit bottom after excavation. Comparing the deformation of supporting piles and the pit in two models, it is found that the deformation calculated by seepage stress coupling method is greater than uncoupled mode and the method could simulate the deformation characteristics of retaining structure and excavation. Finally, the influence of counter weight soil on retaining structure and foundation pit is studied and it shows that deformation can be decreased effectively.