海上风电单桩基础轴向承载特性及软弱土层影响分析

Analysis of Axial Bearing Characteristics of Monopile Foundation for Offshore Wind Turbines and Influence of Soft Soil Layer

随着大直径单桩基础海上风机的广泛应用,桩基础轴向承载特性及复杂地质条件中软弱土层的影响需要进一步研究。利用有限元软件ABAQUS开展数值计算,首先对比了不同极限承载力评价标准,并对土体参数的影响进行敏感性分析,最后讨论软弱土层位置及厚度对承载特性的影响。计算结果表明:采用桩顶荷载-位移曲线所确定的轴向承载力显著小于沉降量控制标准得到的轴向承载力;土体参数中摩擦角对轴向承载力存在重要影响,而弹性模量的增加可有效降低桩基础轴向沉降;土体中软弱土层越靠近桩端,桩基础轴向承载力降幅越大,同时随着软弱土层的厚度增加,轴向承载力将进一步降低,并呈现“加速-匀速-匀速”三段式衰减规律。

With the wide application of offshore wind turbines with large diameter monopile foundation, the axial bearing characteristics of pile foundation and the influence of soft soil in complex geological conditions need to be further studied. The finite element software ABAQUS was used to carry out a series of numerical calculations in this study. Firstly, the different evaluation criteria of ultimate bearing capacity are compared, and the sensitivity analysis of the influence of soil parameters was carried out. Finally, the influence of location and thickness of soft soil layer on bearing characteristics was discussed. The calculation results show that the vertical bearing capacity determined by the loaddisplacement curve of the pile top is significantly smaller than that obtained by the settlement control standard. The friction angle of soil has an important influence on the vertical bearing capacity, and the increase of elastic modulus can effectively reduce the axial settlement of monopile. The closer the soft soil is to the pile end, the greater the decline of the axial bearing capacity of monopile. At the same time, as the thickness of the soft soil layer increases, the axial bearing capacity will further decrease and show a three-stage attenuation law of “acceleration-uniform speed-uniform speed”.