桩顶荷载及温度循环对黄土地基中能量桩承载性状影响研究

Study on influence of pile top load and temperature cycle on bearing behavior of energy pile in loess foundation

为对比分析未经过温度循环的普通桩与能量桩竖向承载变形性状,开展黄土地基中能量桩温度循环试验。模型桩为现浇钢筋混凝土灌注桩,黄土为人工配制重塑黄土。研究结果表明:温度循环弱化黄土地基中能量桩桩身侧阻、增强能量桩桩底端阻,温度循环过程中桩顶工作荷载越大,桩侧阻的弱化作用及桩端阻的增强作用越大,这导致能量桩的竖向抗压承载力比普通桩有明显的提高。另外,根据模型试验结果,通过数据拟合建立桩土界面摩阻力-桩土相对位移及桩端土反力-桩端沉降双曲线函数模型,并确定模型参数,其函数计算结果与试验结果对比表明本文模型能合理反映温度循环及桩顶工作荷载大小对桩基承载力的影响。研究结果可为黄土地区能量桩的安全设计提供一定参考。

In order to compare and analyze the vertical bearing deformation behavior of ordinary pile and energy pile without temperature cycle,the temperature cycling test of energy piles in loess foundation was carried out.The model piles were the cast-in-place reinforced concrete filling piles,and the loess was the artificially prepared remodeling loess.The results show that the temperature cycle weakens the lateral resistance of energy pile body in the loess foundation,and enhances the end resistance of energy pile.The greater the working load at the pile top during the temperature cycle,the greater the weakening effect of pile side resistance and the enhancement effect of pile end resistance,which leads to a significant increase in the vertical compressive bearing capacity of energy pile compared with that of ordinary pile.In addition,according to the results of model test,the hyperbolic function model of the pile-soil interface friction resistance with pile-soil relative displacement and the pile end soil reaction force with pile-end settlement was established through data fitting,and the model parameters were determined.The comparison between the calculation results of the hyperbolic load transfer function and the experimental results presents that the proposed model can reasonably reflect the influence of temperature cycle and working load on pile top on the bearing capacity of pile foundation.The research results can provide some reference for the safety design of energy piles in loess area.