(1. 河海大学 岩土力学与堤坝工程教育部重点实验室，江苏 南京，210098；
2. 绍兴文理学院 土木工程学院， 浙江 绍兴，312000；
3. 墨尔本大学 墨尔本设计学院，维多利亚，澳大利亚)
摘 要: 根据等截面圆形灌注桩(UCSC桩)Q-S曲线的统计资料，总结其数学特征，指出Q-S曲线传统双曲线模型产生X型误差的缺陷。提出UCSC桩Q-S曲线的一个3参数复合对数模型，该模型是一个通过零点、单调递增且有上界的凸函数。对多个UCSC桩单桩实测静载Q-S曲线进行拟合对比。研究结果表明：该模型大大减小甚至消除了传统Q-S曲线双曲线模型产生的X型拟合误差；拟合结果与实测UCSC桩静载Q-S曲线吻合良好；该模型能够通过对Q-S曲线前半段的数据点拟合，实现对其尾部曲线高精度预测，这对试桩未达破坏时确定UCSC桩承载力有重要意义。
关键字: 桩基础；UCSC桩；Q-S曲线；承载力；复合对数模型
（1. Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering,
Hohai University, Nanjing 210098, China;
2. School of Civil Engineering, Shaoxing University, Shaoxing 312000, China;
3. Melbourne School of Design, Melbourne University, Victoria, Australia）
Abstract:According to field tested data, mathematical property of the static load-settlement curve (Q-S curve) of cast-in-place pile with uniform-circular cross section (UCSC pile) was summarized, and X-shape fitted error of traditional hyperbolic model was analyzed. The three-parameter composite logarithmic model for UCSC pile’s Q-S curve was presented, which is characterized by going through point, monotone increasing, convex and up limited function. The fitted values of field investigated static loading data of many UCSC piles were compared with the measured values. The results show that the composite logarithmic model can minimize the X-shape fitted errors caused by hyperbolic model. The presented fittings are in agreement with the investigated UCSC pile’s Q-S curves. The presented model can precisely predict the end part of the Q-S curve of UCSC pile after fitting its initial part, which is helpful to determining bearing capacity of UCSC pile in static load test.
Key words: pile foundation; UCSC pile; Q-S curve; bearing capacity; composite logarithmic model
