楔形桩与圆柱形桩复合地基承载性状对比研究

基于剪切位移法，引入Mylonakis & Gazetas桩-土相互作用及Winkler地基模型，导出了复合地基中桩-桩、桩-土及土-土相互作用柔度系数；在此基础上，提出了一种综合考虑桩-土-垫层共同作用的复合地基分析方法，并利用Matlab软件编制了相应的计算程序。为了验证该方法的可行性，对楔形桩和圆柱形桩复合地基进行了模型对比试验，并利用该方法对两个模型试验进行了计算分析，试验及理论结果均表明，桩顶平面处的桩间土反力保持着类似天然地基的马鞍形分布，圆柱形桩复合地基的承载力明显低于楔形桩复合地基的承载力，同时，圆柱形桩复合地基的桩土平均应力比明显高于楔形桩复合地基的桩土平均应力比，楔形桩对缓解复合地基中桩顶应力集中，充分利用天然地基的承载能力具有良好的调节作用。

Contrast research of bearing behavior for composite foundation with tapered piles and cylindrical piles

Based on the shear displacement method, the Mylonakis &; Gazetas model for mutual action between pile and soil, and the Winkler foundation model were introduced; then the flexible factors for mutual actions between pile and pile, pile and soil, soil and soil were provided. An analysis method to pile-soil-cushion mutual action in the composite foundation was deduced; and the correlated program was also developed by Matlab software. In order to validate the feasibility proposed approach in this paper, two static load model tests for the composite foundation with tapered piles and cylindrical piles were done in laboratory respectively; and the method was used to analyze two models. Experimental and theoretical results indicated the reaction force distribution of surrounding soil in pile-top plane keeps saddle type, which is similar to natural foundation; the bearing capacity of composite foundation with tapered piles is higher than that of composite foundation with cylindrical piles; and the average pile-soil stress ratio of composite foundation with tapered pile is lower than that of composite foundation with cylindrical piles obviously; tapered pile can relief pile-tip stress concentration in composite foundation effectively; and it has good regulation on using the bearing capacity of natural foundation fully.