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Geddes方法是我国桩基工程实践中常用的计算群桩沉降的一种弹性理论方法,其原理简单,易于应用,但其也有着比较明显的缺点。首先,Geddes法没有考虑桩径的影响,计算时会在桩端平面产生很大的应力集中;其次,Geddes法中假设的侧摩阻力分布模式过于简单,与工作状态下长桩的侧阻分布差别较大。为了解决这些问题,在Geddes方法的基础上,首先假设端阻力沿桩端平面均匀分布,桩侧摩阻力沿桩侧表面分布,采用数学积分与高斯积分相结合的方法计算地基附加应力,改善应力集中的影响;其次通过对Geddes方法原有侧阻分布模式的几何叠加,得到桩侧摩阻力两段式分布时地基附加应力的计算公式。计算表明,改进后的Geddes方法计算桩基沉降要比原有的Geddes方法计算值小。
Geddes method is a kind of elastic theory method commonly used in pile foundation engineering practice in China to calculate settlement of pile groups. Its principle is simple and easy to apply, but it also has some obvious shortcomings. First of all, the Geddes method does not consider the influence of pile diameter, which will result in great stress concentration in the pile tip plane. Second, the assumed lateral frictional resistance distribution model in Geddes method is too simple. The difference is bigger. In order to solve these problems, on the basis of Geddes method, firstly, it is assumed that the end resistance is distributed uniformly along the plane of pile tip and the friction of pile side is distributed along the side surface of the pile. The method of combining mathematical integral with Gaussian integral is used to calculate the additional stress and stress Secondly, through the geometrical superposition of the original lateral resistance distribution model of Geddes method, the calculation formula of the additional stress of foundation when two-stage frictional resistance of pile is obtained is obtained. The calculation shows that the improved Geddes method is less than the original Geddes method to calculate pile foundation settlement.