【作者】 王秀哲；

【导师】 薛国亚； 龚维明；

【作者基本信息】 东南大学 ， 岩土工程， 2005， 硕士

【摘要】 随着高层、超高层建筑和大跨桥梁的建设,具有高承载力的超长钻孔灌注桩被大量使用,但其理论研究却远远滞后于工程实践,需要对超长钻孔灌注桩的承载变形机理进行深入的研究,本文着重对超长钻孔灌注单桩的荷载-沉降曲线进行了研究。本文首先对超长钻孔灌注桩的研究现状和桩基计算理论给予综合评述。从简单、实用的目的出发,本文提出了超长钻孔灌注桩桩-土相互作用的力学模型,将桩侧传递函数简化为线弹性全塑性模型,桩端传递函数简化为弹性硬化模型,用荷载传递法推导出均质土中超长钻孔灌注桩轴向荷载-沉降曲线的解析解。且在此基础上,推导出成层土中超长钻孔灌注桩荷载-沉降曲线的解析解。对荷载-沉降曲线解析解中的描述桩土体系特性的三个无量纲特征量剪切比刚度α1、压缩比刚度β和极限剪切比刚度γ进行了讨论,并给出解析解中抗剪刚度系数λ等参数的确定方法。应用大型有限元程序,采用土的Drucker-Prager模型,建立超长钻孔灌注桩分析计算的桩土模型,系统分析了竖向荷载作用下桩长、桩径、桩体弹性模量、桩土模量比和桩端土层对超长钻孔灌注单桩荷载-沉降曲线的影响,研究了超长钻孔灌注桩的荷载-沉降特性、侧阻和端阻的发挥性状,得出一些具有实际指导意义的结论。结合一个具体工程实例,对超长钻孔灌注单桩的实测荷载-沉降曲线进行了理论拟合,验证本文推导出的公式在工程中是适用的。更多还原

【Abstract】 With the development of super-tall building and long-span bridges, it is necessary to mass- use super-long bored piles because of their high bearing capacity. But the research on theory of super-long bored piles is far behind the development of practice. So, the research on mechanism of bearing and deformation of super-long piles is demanded. Axial loading-settlement curve of super-long bored single pile is studied in this paper.The research actuality of super-long piles and the pile calculation theory are discussed firstly and a comprehensive commentary is given. Mechanics model of pile-soil system of super-long bored single pile is put forward, pile shaft loading transfer function and pile base loading transfer function may be simplified by elastic-plastic model and elastic-hardening model respectively in order to simplification and practicality, a set of analytics of the axial loading-settlement curve of super-long bored pile in homogeneous soil are established. Based on this, the analytics of loading-settlement curve of super-long bored pile in layered soil are also established. Three dimensionless parameters of the analytics of axial loading-settlement curve are also proposed, which may be used to describe the characteristic of a pile-soil system. Meanwhile, the method of calculating the parameters of analytical equation is given.By using the great finite element method (FEM) program and the Drucker-Prager model, the pile-soil model of super-long bored pile is established, factors that influence axial loading-settlement curve of super-long bored pile under vertical loading are analyzed systemically, the characteristics of loading-settlement curve, pile shaft resistance and pile base resistance are studied, some practical guidance conclusions are acquired.With a practical engineering, a good agreement between calculation results and testing results of 1 super-long bored single pile is found, and shows the analytics established in the thesis may be used to practical engineering.更多还原