软土地基水闸底板有限元分析的桩基模拟方法

Pile foundation simulation method for finite element analysis of sluice floor on soft-soil ground

传统分析方法中,采用等参单元模拟软土地基群桩基础的方法既不经济且夸大桩的刚度,为能对桩基进行合理高效地模拟,本文提出了一种考虑桩、土及底板相互作用的内置桩单元法。采用梁单元位移模式,根据桩单元节点在土或底板等参单元中的局部坐标,建立桩单元包含转角的节点位移与土或底板节点位移之间的关系,进一步代入到有限元整体控制方程中求解。结果表明,通过本文建立的位移转换模式,可以利用梁单元对考虑复杂的桩、土和上部结构相互作用情况的桩基进行模拟,在保证精度的同时简化了建模步骤,降低了对网格密度的要求。研究表明,采用本方法可以验证软土地基上水闸底板受力分析时桩基础用梁单元位移模式模拟的合理性和有效性,为软土地基上桩基的快速分析计算提供了一种新方法。

As the method of adopting isoparametric elements to simulate the pile foundation of soft soil foundation is not only uneconomical,but also overstates the stiffness of the pile,a built-in pile element method considering the interaction among pile,soil and floor is put forward herein,so as to make a reasonable and efficient simulation of the pile foundation.By means of the mode of beam element displacement,the relationship between the node displacement of pile element including rotating angle and the displacement of the soil or floor node is established in accordance with the local coordinates of the pile element nodes in the isoparametric elements of soil or floor,and then it is solved through further substituting it into the finite element global governing equation.The result shows that through the displacement conversion mode established herein,the pile foundation with the consideration of the complicated interaction among pile,soil and upper structure can be simulated with beam element,thus the modeling step is simplified and the requirement on the mesh density is lowered at the same time of ensuring precision.The study indicates that both the reasonability and the effectiveness of the simulation made with the mode of the beam element displacement during the stress analysis of the sluice floor on soft ground can be verified by this method,while a new method is provided for the quick analysis and calculation of pile foundation on soft soil ground as well.