复合荷载作用下桩反应的数值分析

Numerical Analysis of the Response of Piles under Combined Loads

在竖向和水平荷载复合作用下,计算桩的水平承载力和截面弯矩是一个比较复杂的问题,目前相关的实验室和现场试验研究还很少.现行的设计方法都是单独考虑竖向和水平荷载的影响.本文利用三维有限元程序MARC对这个问题进行了研究,说明了竖向荷载和长细比对桩侧向反应的显著影响.有限元分析分别在均质黏土和均质砂土中进行,发现在砂土中竖向荷载甚至对长细比超过30的长桩的影响也很显著,而在黏土中当桩的长细比超过15时,这种影响已经不明显.水平受荷单桩上的设计弯矩值也在很大程度上取决于作用在桩上的竖向荷载等级.

It is a complicated problem to calculate the horizontal bearing capacity of the pile and the bending moment developed in its section under the combined action of vertical and horizontal loads, and now related study in laboratory and field test is rather limited. The current method of design is to consider the vertical and horizontal loads independent of each other. This paper, by using a three-dimensional finite-element program MARC,presents some results that show the significant influence of vertical loads and slendemess ratio on a pile＇ s horizontal response. The analyses were performed in both homogeneous clayey soils and homogeneous sandy soils. It was found that the effect of vertical loads in sandy soils is significant even for long piles, which are as long as 30 times the pile width, while in the case of clayey soils, the effect is not significant for piles beyond a length of 15 times the width of the pile. The design bending moments in the laterally loaded piles were also found to be dependent on the level of vertical load on the piles.