深厚软黏土地基中大直径单桩基础现场水平受荷试验及 p-y 曲线适用性研究

基于某海上风电场开展的单桩水平受荷特性现场试验,研究了深厚软黏土中2.4. m 大直径钢管桩荷载-位移响应、桩身挠度及桩身弯矩规律；探讨了m法、 API 规范法和双曲线型p-y曲线在软黏土地基中的适用性,并建立数值模型对不同直径单桩基础的水平承载力贡献因素进行分析。结果表明: API 规范法与双曲线型p-y曲线在浅层土中p-y曲线初始刚度与桩周土抗力偏大,双曲线型p-y曲线在一定深度下能够较好地预测土反力随位移的变化关系,m法与双曲线型p-y曲线计算得出的水平位移较实测值偏小,结果偏向不安全, API 规范法计算结果相比实测值较大,计算结果较为保守；随着桩径增大,单桩基础的侧摩阻力和基底抗力对水平承载力贡献也会随之增大,双曲线型p-y曲线会严重低估单桩的水平承载力。

Field horizontal loading test and p-y curve applicability of large-diameter single pile foundation in deep soft clay groundsill

Based on the field test of horizontal loading characteristics of a single pile in an offshore wind farm, the load-displacement response, pile deflection and bending moment of a 2.4 m large-diameter steel-pipe pile in deep soft clay groundsill were studied. The applicability of m method, p-y curve and hyperbolic curve recommended by the API specification for soft clay foundation is discussed. Numerical models were established to analyze the contribution factors of horizontal bearing capacity of single pile foundations with different diameters. The results showed that the initial stiffness of pile and soil resistance in the shallow soil p-y curve from the API specification method and the hyperbolic is larger, and the hyperbolic under a certain depth can better predict the changing relationship of soil reaction force with displacement. The calculated horizontal displacement of m method and hyperbola is smaller than measured values, tending to be unsafe results, while the calculated results of the API specification method are larger compared with the measured values, more conservative. With the increase of pile diameter, the contribution of lateral friction and foundation resistance to the horizontal bearing capacity of single pile foundation will also increase, and the p-y curve method will seriously underestimate the horizontal bearing capacity of single pile.