【摘要】 海上风电单桩的长期累积变形特性是设计中需重点考虑的关键问题，而现有规范未能考虑循环次数与循环幅值对单桩累积变形的影响。针对这一问题，通过数值分析，并结合自定义场变量子程序，研究了不同循环幅值作用下不同单桩尺寸的累积变形情况。具体结论如下：在软土中存在循环荷载阈值，当循环幅值ξ≤0.2时，单桩在循环荷载作用下的长期累积变形问题可忽略；而当循环幅值为0.4和0.6时，单桩会产生明显的累积变形，且变形呈幂函数规律逐渐增大，增速随循环次数的增加而减缓；当桩长一定时，累积变形随桩径增加而增加；当桩径一定时，增加桩长能有效减少累积变形的产生。然而，当循环幅值为0.4时存在桩长阈值，即当长径比L/D≥15后再增加桩长将无法进一步减少累积变形；同一桩径在200次循环荷载作用下，循环幅值为0.6时产生的累积变形是循环幅值为0.4时的6倍。更多还原

【Abstract】 The long-term cumulative deformation characteristics of offshore wind turbine monopile foundations are key issues that need to be considered in design. However, existing standards do not take into account the impact of the number of cycles and the amplitude of cycles on the cumulative deformation of monopiles. To address this issue, this study conducts numerical analysis and uses a custom field variable subroutine to investigate the cumulative deformation of monopiles with different sizes under different cyclic amplitudes. The specific conclusions are as follows: A threshold for cyclic loading exists in soft soil. When the cyclic amplitude ξ≤0.2, the long-term cumulative deformation of monopiles under cyclic loading can be neglected. However, when the cyclic amplitudes are 0.4 and 0.6, the monopile undergoes significant cumulative deformation, and the deformation increases according to a power function, with the rate of increase slowing down as the number of cycles increases. When the pile length is fixed, the cumulative deformation increases as the pile diameter increases. When the pile diameter is fixed, increasing the pile length effectively reduces the occurrence of cumulative deformation. However, when the cyclic amplitude is 0.4, a pile length threshold exists. Specifically, when L/D≥15, further increasing the pile length will not reduce the cumulative deformation. Under 200 cycles of loading, the cumulative deformation generated by a cyclic amplitude of 0.6 is six times that generated by a cyclic amplitude of 0.4 for the same pile diameter.更多还原