Dynamic characteristics of seabed soil under seismic load arevery important for the overall stability of the offshore wind turbine foundation. In this study, the horizontal bearing capacity and its corresponding soil deformation around the large-diameter monopile, where withstandsa transient high frequency seismic load, are simulated using a numerical method. During the numerical analysis in this paper, first a dynamic boundary surface model of saturated soil is derived instead of the empirical strength degradation method, and then a pile-soil contact model is considered instead of no-slip tie assumption. On the basis of the numerical results, an empirical degradation coefficient for the horizontal ultimate bearing capacity of monopile is proposed in this paper, which can well evaluate the effect of seismic load on the bearing capacity. Along the axis direction of the monopile, an intensive study about deformation law and failure mechanism of the seabed soil is analyzed by comparing somekey points at different crossing sections.Finally, some parameters which may affect the bearing capacity and the excesspore pressure are discussed. It can be found that the horizontal bearing capacity of the monopile can be obviously improved by increasing the buried depth than the diameter of monopile, and the seismic load has great influence on the soil deformation law around the monopile.

地震作用下海床土壤的动力特性对于海上风力发电机基础的整体稳定性非常重要。在这项研究中，使用数值方法模拟了承受瞬态高频地震载荷的大直径单桩周围的水平承载力及其对应的土壤变形。在本文的数值分析中，首先导出了饱和土的动态边界表面模型，而不是经验强度退化方法，然后考虑了桩-土接触模型，而不是无滑移联系假设。在数值结果的基础上，提出了单桩水平极限承载力的经验衰减系数，可以较好地评价地震荷载对承载力的影响。沿单桩轴线方向，通过比较不同横断面的一些关键点，深入研究了海床土的变形规律和破坏机理。最后，讨论了一些可能影响承载力和过大孔隙压力的参数。可以发现，通过增加埋藏深度比增加单桩的直径，可以明显提高单桩的水平承载力，地震荷载对单桩周围的土壤变形规律有很大的影响。