考虑流固耦合作用的钢板桩基坑变形模拟分析

Simulation Analysis of Steel Sheet Pile Foundation Pit Deformation in Consideration of Fluid-structure Coupling Effect

在软土地区深基坑施工过程中,由于地下水渗流场变化的影响,基坑失稳破坏是较为常见的灾害。该文采用等刚度替换法,将拉森钢板桩等效为矩形截面钢板,并借助有限元软件ABAQUS,结合某工程算例探讨了渗流应力耦合作用下基坑周边土体孔压场及变形场的分布特性。结果表明,在地下水位以上开挖时,地下渗流场基本没变化,是否采用渗流应力耦合,土体变形结果基本一致;在地下水位以下开挖时,随着开挖深度加大,渗流应力耦合计算结果与未考虑渗流影响的计算结果偏差越大,说明在深水区,考虑渗流应力耦合的必要性和合理性。未考虑渗流应力耦合作用的计算结果偏于不安全,考虑渗流应力耦合作用可更准确地反映基坑渗流与变形情况。

The unstability of foundation pit because of the change of groundwater seepage field is one of the frequently encountered engineering disasters in the construction of soft soil regions. This paper uses the equal stiffness substitution method to make the larssen steel sheet pile to equivalent rectangular section steel plate,with the help of FEM software ABAQUS,as well as combination of an engineering,the distribution characteristics of deformation and water pressure field of soil around the pit are discussed with considering seepage stress coupling effect. The results show that： there are no much differences in seepage field when the excavation is above the groundwater level. Using the seepage stress coupling or not,the deformation of soil are basically consistent; Excavation under the groundwater level,with the increasing of excavation depth,the deviation is bigger in the calculation result with considering the seepage stress coupling or not. It shows that in deep water area it is essential and reasonable to consider the seepage stress coupling. Without considering the seepage stress coupling,the calculating result is unsafety. The seepage and deformation situation are reflected more accurately by considering the seepage stress coupling.