海上大直径单桩基础p-y曲线修正

海上风力发电作为一种具有前景的可再生能源,目前的增长十分迅速。超大直径钢管桩是目前海上风机结构的最常用基础型式,API规范建议的p-y曲线法是目前评价钢管桩水平承载能力的主要方法,但其对大直径桩基的适用性有待探讨。本文通过开展系列三轴CU试验标定了等向硬化模型中的各个参数,并通过与实测土体应力-应变曲线的对比验证了建立的等向硬化模型的可靠性。基于该模型采用三维有限元方法分析了黏土中大直径桩基的水平受荷特性,结果发现规范方法低估了大直径刚性桩p-y曲线的初始刚度和土体极限抗力,因此考虑土体强度不均匀性、桩土间粗糙度及桩径效应的影响,对极限土抗力pult和桩体变形参数yc进行了修正,提出了大直径刚性桩修正p-y曲线计算方法。基于现有离心模型试验验证了所提方法的合理性,为海上风机大直径单桩水平承载力计算提供了参考。

A modified p-y curve method for offshore large-diameter monopile foundations

Offshore wind power has a huge potential growth as a kind of renewable energy. At present, large-diameter steel monopile is the most commonly used type of foundation for offshore wind turbine. The conventional method for assessment of steel-pile lateral performance is the application of p-y curves recommended in API. However,the applicability of the API method for large-diameter monopiles needs to be further studied. A series of CU triaxial tests were conducted to calibrate the parameters of isotropic hardening model,which has been validated against the test results of stress-strain soil behavior. Based on this model, 3D finite element analyses are performed for the behavior of the laterally loaded large-diameter monopiles. The FEA results find the guideline method underestimate the initial stiffness and the ultimate pressure acting on the rigid large-diameter monopiles. According to the effect of soil shear strength gradient, pile roughness and pile diameter,the soil ultimate pressure p_ult and pile deformation parameter yc were reevaluated, and a modified p-y curve method for large-diameter rigid monopiles was presented. Based on the published centrifuge model test results, the proposed method was proven to be reasonable, suggesting that it could be used as an engineering analysis approach for evaluating the lateral bearing capacity of offshore wind large-diameter monopile foundations.