基础理论与实验研究

考虑桩径和桩侧摩阻力分布的改进Geddes 桩基沉降分析方法

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  • 1. 同济大学 地下建筑与工程系,上海 200092;2. 华东建筑设计研究院有限公司 地基基础与地下工程设计研究中心,上海 200002
张瑜,男,1992年生,硕士研究生,主要从事桩基沉降计算理论方面的研究工作。

收稿日期: 2015-03-31

  网络出版日期: 2018-06-14

基金资助

国家科技支撑计划课题(No.2012BAJ01B02)。

A modified Geddes’s method for estimating settlement of pile foundation considering influences of pile diameter and distribution pattern of shaft resistance

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  • 1. Department of Geotechnical Engineering, Tongji University, Shanghai 200092, China; 2. Department of Underground Structure & Geotechnical Engineering, East China Architectural Design & Research Institute Co., Ltd., Shanghai 200002 China

Received date: 2015-03-31

  Online published: 2018-06-14

摘要

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。

本文引用格式

张 瑜 ,吴江斌 ,蔡永昌, . 考虑桩径和桩侧摩阻力分布的改进Geddes 桩基沉降分析方法[J]. 岩土力学, 2015 , 36(S2) : 406 -412 . DOI: 10.16285/j.rsm.2015.S2.057

Abstract

Geddes’s method is widely applied to estimate the settlement of pile group in China with its simple principle and easy realization. However, Geddes’s method has its own obvious shortcomings. The influence of pile diameter is not considered in Geddes’s method which can produce great stress concentration on the pile tip. Moreover, the distribution of shaft resistance of long piles under vertical working load is quite different from the suggested one of Geddes’s method. In order to solve these problems, based on Geddes’s method, a modified assumptions is presented, i.e. the end resistance uniformly distribute on the pile tip and the shaft resistance distributes on the side surface of the pile. Mathematical integration and Gauss integration are applied to estimate additional stress in the soil, which can significantly decrease the influence of stress concentration. Meanwhile, calculation formula of additional stress in the soil of bilinear distribution pattern is deduced by the combination of Geddes’s method. Case studies show that the settlement predicted by modified Geddes’s method is smaller than that predicted by Geddes’s method.
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