海上风电单桩基础土相互作用特性影响因素分析

采用有限元软件ABAQUS建立了海上风电单桩基础与土相互作用数值计算模型,将波浪、洋流及风荷载等效成双向对称循环荷载,研究了水平循环荷载作用下不同因素对桩身水平位移、剪力和弯矩的影响规律。研究表明,随着循环荷载比的增加,桩身位移零点和桩身剪力反弯点沿埋深逐渐下移,桩身弯矩最大值点位于浅层土体;不同荷载频率时桩身位移在零点以上变化较大,桩身弯矩随着频率的增加逐渐增大;单向循环荷载作用下桩身位移最大,双向对称循环荷载作用下桩身位移最小;壁厚较小时对桩身水平位移影响较大;在位移零点之上范围内可以考虑设计"上厚下薄"的钢管桩,以减小桩身水平位移;不同桩壁厚时桩身剪力曲线在埋深约6D处出现交点,且泥面处桩身弯矩变化不明显。

Analysis of influencing factors of monopile foundation-soil interaction characteristics for offshore wind power

A numerical calculation model of monopile foundation-soil interaction for offshore wind power was established by finite element software ABAQUS. The wave, ocean current and wind load were equivalent to the bidirectional symmetrical cyclic load. The variation rules of horizontal displacement, shear force and bending moment along the pile shaft under different influence factors of horizontal cyclic load were studied. The results show that with the increase of cyclic load ratio, the zero point of pile displacement and the negative bending point of pile shear force move down gradually along the buried depth, and the maximum bending moment point of pile body is located in the shallow soil. At different load frequencies, the displacement of pile body varies greatly above the zero point, and the bending moment of pile body increases with the increase of frequency. The displacement along the pile shaft is the largest under unidirectional cyclic load and the smallest under bidirectional symmetric cyclic load. When the wall thickness is small, the horizontal displacement of pile is greatly affected. In order to reduce the horizontal displacement along the pile shaft, variable section steel pipe piles with "upper thickness, lower thinness" can be designed in the range above the zero of displacement. When the pile wall thickness is different, the shear force curve along the pile shaft intersects at the buried depth of about 6D, and the change of bending moment along the pile shaft at the mud surface is not obvious.