组合桩极限承载力计算方法的探讨

组合桩是钢筋混凝土桩芯插入水泥土搅拌桩复合而成的新型桩。因组合桩承载力影响因素复杂,其极限承载力计算方法各异。为此,依据各地试验数据并参照各地规程及组合桩承载力机理,通过对桩长范围内的平均侧摩阻力和极限承载力之间关系的分析,引入桩周侧摩阻力调整系数ηs,提出了组合桩竖向承载力的计算公式。通过分析每一组试验的ηs平均和qsp平均,采用数理统计的方法,拟合出ηs平均和qsp平均的关系曲线,并通过各个桩理论承载力和试验承载力散点图的对比,表明所提出的组合桩竖向承载力的计算公式不仅符合实际,而且计算简单,有利于工程人员掌握使用。

Discussion on Method Calculating Limit Bearing Capacity of Composite Pile

Composite pile is a new kind of pile which is formed by inserting a reinforced concrete pile core into cement-soil mixing pile. Since the factors influencing the bearing capacity thereof are complex, there are diverse methods calculating the limit bearing capacity. Therefore, based on the test data and the regulations in many places and the mechanism of composite pile’s bearing capacity, with the analysis of relationship between the average side frictional resistance ηs within the range of pile length and the limit bearing capacity, this paper introduced adjustment factor for pile’s side resistance, and gave a formula of composite pile’s vertical bearing capacity. By analyzing the ηsave and ηspave of each group of tests, the ηsave vs. ηspave Curve was obtained through fitting by means of mathematical statistics. Next, depending on the comparison between the theoretical bearing capacity of each pile and the scatter plot of test values, it is showed that the formula proposed herein is of availability and simple, and easy to be understood and used by engineers.