桩基重力式支护结构的不同计算模型

桩基重力式支护结构由重力式胸墙和双排桩组成,是一种半刚性半柔性支护结构。对该结构的设计,相关单位根据规范采用平面钢架弹性支点法计算下部双排桩,同时将上部胸墙简化为悬臂梁进行计算,但由于胸墙为刚性体,受力特征及对双排桩的约束与悬臂梁不同。为了系统研究该结构在不同计算模型中的变形及内力分布特征,对比规范设计和实体模型的计算结果。结果表明:参照相关规范设计时,上部胸墙产生线性位移,后排桩的弯矩及剪力都大于前排桩;而在实体计算模型中,上部胸墙发生平动位移模式,由于基坑开挖受到主要的土压力差作用,前排桩产生的弯矩和剪力都大于后排桩。

Different calculation models of pile foundation gravity support structure

The pile-based gravity support structure consists of a gravity chest wall and a double-row pile,is a semi-rigid semi-flexible support structure.For the design of the structure,the relevant unit reference specification uses the plane steel frame elastic fulcrum method to calculate the lower double-row pile,at the same time the upper chest wall is simplified as the cantilever beam for calculation.But the mechanical characteristics and the constraints on double-row piles are different from that of the cantilever beam because the chest wall is rigid body.In order to systematically study the deformation and internal force distribution characteristics of the structure in different calculation models,the normalized design and the calculation results of the solid model are compared.The results show that:according to the relevant specifications,the upper chest wall produces linear displacement,and the bending moment and shearing force of the rear pile are larger than that of the front pile;in the solid calculation model,the upper chest wall has a translational displacement pattern,so the bending moment and shear force of the front pile are greater than those of the back pile because the foundation pit excavation is affected by the main earth pressure difference.