柔性基础下刚性桩复合地基沉降计算

Calculation of Settlement of Composite Foundation with Rigid Piles under Flexible Ground

针对刚性桩复合地基中桩、土、垫层相互作用特点,通过拟合桩土单元体竖向相对位移分布函数,引入弹塑性荷载传递模型,并考虑桩体的上刺与下刺变形以及中性点和桩土界面变形协调,对桩土相对位移变形形式、桩侧摩阻力变化规律、桩端土反力模型作一定的简化,建立出刚性桩桩复合地基沉降计算的基本微分方程,进而提出了一种新的能考虑桩-土-垫层体系共同作用的柔性基础下刚性桩复合地基沉降计算方法。最后,采用该沉降计算方法对模型试验及工程实例进行分析。结果表明,柔性基础下与刚性基础下刚性桩复合地基变形模式与桩土应力比有很大的差异,沉降计算值及桩土应力比与实测值吻合较好,且该方法计算工作量小,能够对刚性桩复合地基沉降量计算提供参考。

According to the character of the interaction of the pile, soil and cushion in composite foundation, by fitting the vertical relative displacement distribution function of pile-soil element and introducing an elastic-plastic load transfer model, deformation form of the pile-soil relative displacement, friction variation of pile and pile-side soil reaction force model were simplified, and a basic differential equation of settlement calculation of the rigid pile composite foundation was established in consideration of both upward and downward penetration displacements of piles and the coordination of deformation of neutral point and the pile-soil interface. Then, a new method of calculating the settlement of the rigid pile composite foundation considering the interaction of pile-soil-cushion system was developed. At last, this new method was applied to the analysis of a model experiment and a project example, and the results show that （ 1 ） there exist great difference between the deformation mode and pile-soil stress ratio of rigid pile composite foundation under flexible ground and those under rigid ground; （2） the calculated results are close to the measured values. This method can reduce the calculation and provide a reference for the settlement calculation of rigid pile composite foundation.