摘要
众多柔性桩有效桩长的计算方法都是基于单桩受荷情况的假设,没有考虑桩间土顶荷载对桩体的侧限作用,因而计算出来的有效桩长与实际情况相差甚远。本文基于Mindlin和Boussinesq应力解的联合方法,同时考虑桩间土顶荷载和群桩效应的影响,经推导得出了计算复合地基中任意深度位置的附加应力分布的计算方法。根据弹性理论分别计算桩土压缩量,并考虑在刚性基础条件下桩土位移的协调关系,得到了在刚性基础下柔性桩复合地基有效桩长计算公式。由于本文方法考虑了桩侧摩阻力和群桩效应的作用,增大了桩间土对柔性桩的侧限作用,从而有效桩长有所提高。数值计算结果表明,当桩土模量比Ep/Es取值为15时,采用本文方法得到的有效桩长为10.1m,比用其它方法得到的结果增大1倍左右。
A lot of methods for calculating the effective length of flexible pile in composite foundation are almostly based on hypothesises that loads are only put on the top of pile and effect of loads on the surface of soil between piles is ignored , so there is a large difference between results calculated by theory and measured in site. Firstly, a new method which can be used to calculate additional stress in any place of composite foundation is deduced in this paper based on the Mindlin and Boussinesq stress solutions and loads put only on pile top and effect of group piles. Secondly, a formula for calculating effective length of flexible pile under stiff foundation is set up based on elastic theory and displacement cooperation relations. Because of the action of side frictional resistance of piles and effect of group piles are thought about and effect of skin friction is enlarged, the length of effective length by method of this paper is longer than length calculated by method of Duan＇s. Numerical calculation result also indicates that effective length calculated by method in this paper is about 10.1 meters which is about two times of length calculated by other methods when Ep/Es is about fifteen.
出处
《勘察科学技术》
2006年第6期6-9,13,共5页
Site Investigation Science and Technology
