上砂下黏地层中桩‑筒复合基础V‑H承载特性∗

海上风机基础不仅受自重等竖向力V 作用，也因水流、波浪和风等影响而承受水平荷载H。为探讨上砂下黏地层中一种由单桩和吸力筒组成的新型海上风机桩-筒复合基础受V?H 组合作用时的承载特性，自主设计完成了一系列室内桩-筒复合基础V?H 组合加载模型试验，获得不同组合参数下桩-筒复合基础的荷载-位移曲线和桩身弯矩分布曲线，并绘制出V?H 承载力包络线。在此基础上，采用ABAQUS 建立了上砂下黏地层中桩-筒复合基础三维数值分析模型，经模型验证与参数分析，进一步讨论了砂土厚度、筒径、筒高以及加载高度等参数对桩-筒复合基础承载特性的影响曲线，并拟合出桩-筒复合基础承载力简化计算公式，分析结果表明：桩-筒复合基础能显著提高桩身水平承载力，增幅达30%~90%，且增加筒径比增加筒高更有利于提高基础水平承载力；上部砂土层较厚时，桩-筒复合基础存在一个使复合基础水平承载力达到最大的预加竖向荷载最佳值，其值随不同载荷工况在（0.4~0.7）Vult范围内变化。

Loadbearing Characteristics of Pilebucket Composite Foundationunder VH Loading in Sand Over Clay Soil Deposit

Offshore wind turbine foundations are subjected to not only vertical forces (V), such as deadweight, but also horizontal loads (H) under the influence of currents, waves, and wind. In order to ex-plore the load-bearing behavior under VH combined loading of a new type of offshore wind turbinecomposite foundation, which was composed of a single pile and suction bucket in sand over clay soildeposits, a series of indoor V-H combined loading model tests for the pile-bucket composite founda-tion were independently designed and completed. Load-displacement curves and bending moment dis-tribution curves for the pile-bucket composite foundation under different combined parameters were ob-tained, and V-H bearing capacity envelopes were drawn. Based on this, ABAQUS was used to estab-lish a three-dimensional numerical analysis model for pile-bucket composite foundation in sand overclay soil deposits. After model validation and parameter analysis, the effects of sand layer thickness,bucket diameter, bucket height, and loading height on its bearing characteristics were investigated. Asimplified formula for calculating the bearing capacity of the pile-bucket composite foundation was de-veloped. The results showed that the pile-bucket composite foundation could significantly improve thehorizontal bearing capacity of the pile by about 30%~90%. Moreover, increasing the bucket diameterwas more efficient in improving its horizontal bearing capacity than increasing the bucket height. Forthicker upper sand layers, an optimal pre-applied vertical load existed that maximized the horizontalbearing capacity of the composite foundation, and it varied in the range of 0.4~0.7 Vult under differentloading cases.