改进的桩土界面荷载传递双曲线模型及其在单桩负摩阻力时间效应研究中的应用

Improved hyperbolic model of load-transfer for pile-soil interface and its application in study of negative friction of single piles considering time effect

摘要: 桩土界面荷载传递模型对预测桩的承载变形性状有重要影响。本文在总结前人研究成果的基础上,改进了反应桩土界面荷载传递性状的双曲线模型。改进后的模型可以描述随着地基土的固结,桩侧土初始剪切刚度随时间增长及桩土界面的加载、卸载循环剪切特性。利用该模型分析了大面积堆载下,在桩顶作用大小不同的竖向荷载以及桩侧土达到不同固结度时再施加桩顶荷载情况下,桩身摩阻力的发展变化规律。研究结果表明:随着地基土的固结,桩身中性点位置处于一个变化过程中,桩顶作用的荷载大小不同,桩身中性点位置也不同;地基土固结一段时间后再打桩能减小桩侧负摩阻力。

Abstract: An improved hyperbolic model of load-transfer for the pile-soil interface was developed.It considered the increase of the initial shear stiffness of the surrounding soil with consolidation and unloading and cyclic behaviour of the interface.The negative skin friction of single pile under different pile head loads was also studied.It was shown that the position of neutral point of pile shaft varied with the consolidation of surrounding soil and the magnitude of pile-head load.The drag force would be reduced when the piles were installed after the soil had reached a certain degree of consolidation.