多支撑基坑开挖对邻近桩基影响的三维数值研究

Three-dimensional Numerical Analysis of Pile Response due to Multi-braced Excavation-induced Lateral Soil Movement

基坑开挖引起的地层移动对临近建筑物下桩基产生影响。运用岩土数值计算软件FLAC3D进行了多支撑围护基坑开挖对邻近桩基影响的三维数值研究,采用修正剑桥硬化土模型模拟土体的非线性应力—应变关系,桩基采用线弹性模型,桩土之间建立接触面。首先在标准问题中对不同桩顶约束条件的邻近桩基进行了研究,然后就围护墙体水平位移量、桩基与基坑开挖面的距离、桩基刚度、桩基长度和桩顶竖向荷载等因素对邻近桩基的影响规律进行了研究,计算结果与先前学者的工程实测结果进行了对比,与工程实测数据在其基本分布方面具有较高的一致性,可为相关的设计施工提供参考。

Basement excavation work for a new building would result in soil movement behind the retaining structure.The soil movement might induce considerable bending moment and deflection on the pile foundations supporting existing structures nearby.In this paper,by using the explicit finite difference code FLAC^3D,the behavior of pile adjacent to multi-braced excavation is investigated.The modified-cam clay constitutive model is employed to model the non-linear stress-strain soil behavior,and the pile is assumed to have linear elastic behavior.The interface model incorporated in FLAC^（3D） code has been used to simulate the soil/pile contact.In ＂standard＂problem,the effects of different pile head constraints on the pile response are investigated,the effects of lateral deflection of the wall,distance from the excavation face,pile stiffness,pile length and axial load on the pile response are also investigated when the pile head is free.The research finding is compared with other published case history and reasonably good agreement is found between them and could be valuable for the design and construction of the excavation.