中文摘要：

通过室内三轴固结排水剪切试验等获得典型剪胀性砂土的力学参数，在此基础上利用有限元软件ABAQUS，开展了近海大直径单桩基础在水平荷载作用下的三维有限元数值分析，揭示了加载过程中桩周土的应力路径，探讨了桩周土内摩擦角、剪胀角及桩土接触面特性等对三维数值分析结果的影响，得到了离心模型试验的验证，进而提出了砂土海床中大直径单桩基础的合理数值分析模型及参数取值方法，并建议风机大直径单桩基础水平承载力确定以变形作为控制标准。在此基础上，利用该数值分析模型分析了现有桩基承载力和变形分析方法对超大直径单桩的有效性，并提出了采用数值分析来确定基础的临界埋深的确定方法。

英文摘要：

A series of consolidated drained （CD） triaxial compression tests on sand with dilatancy is conducted to obtain mechanical parameters. The behaviors of large diameter monopile foundation in offshore under horizontal loading are analyzed using a three-dimensional finite element model with the finite element software ABAQUS. A lot of parameters, like stress path, friction angle, dilatancy angle and the characteristics of soil-pile surface, are taken into consideration to study the soil structure behavior, which is verified with the centrifuge modeling. Then, a reasonable finite element computational model of large diameter monopile foundation under horizontal loading including the parameter selection method of this model is established. Besides, the deformation is proposed as the control criterion to determine the horizontal beating capacity of monopile foundation for the offshore wind turbine. With that, the pros and cons of existing methods for analyzing horizontal bearing capacity and deformation of pile foundation are discussed. Finally, it is suggested to determine the critical embedded length of monopile foundation by numerical analysis.