Introduction  The top grouting jacket pile foundation is a new type of foundation application for offshore wind power jackets on clay seabed. Since the grouting section can bear some loads, its stress and deformation mechanism is significantly different from that of conventional tubular piles. The existing design often ignores the bearing capacity sharing of each part of the foundation, and only treats the grouting section as a hollow tubular pile, ignoring the bearing capacity of the grouting section.

  Method  This paper firstly compared the bearing capacity calculation formulas of existing ocean pile foundations and mesoscale foundations, and analyzed the applicability of various calculation formulas to top grouting jacket pile foundations. Then, a numerical model for top grouting pile foundation on clay seabed was established using the finite element method. The validity of the numerical model was verified by comparing with the field test and centrifugal model test results. Finally, based on the finite element results, the vertical bearing capacity calculation formula suitable for the top grouting pile foundation was analyzed. Effects of various soil strength distributions and length-diameter ratios on the foundation bearing characteristics and bearing proportion were explored.

  Result  Results show that for the soil layers with linearly increasing strength and under various surface strengths, with the increase of the surface strength, the bearing capacity of the grouting section increases, but the bearing proportion of the grouting section gradually decreases. For the same soil layer, the bearing proportion of the grouting section gradually decreases with the increase of the buried depth of pile foundation (length-diameter ratio).

  Conclusion  The bear loads of the grouting section can increase the vertical bearing capacity of jacket pile foundation, which is of great significance for the optimization of jacket pile foundation engineering.