Study on penetration resistance for thin-walled bucket foundation in muddy clay

In view of the problem that the resistance reduction effect of ring stiffeners is not considered in the existing calculation methods of penetration resistance, based on the field penetration date of thin-walled bucket foundation with ring stiffeners and combined with the field installation situation, the resistance reduction effect of the angle iron ring stiffeners on the skin friction resistance was explored, the calculation method of the penetration resistance considering the resistance reduction coefficient β was proposed. The results show that because the resistance reduction effect of ring stiffeners is not considered, the calculation results of the standard and theoretical equation method are larger than the measured resistance. The end resistance increased by ring stiffeners is about 55%–65% of the end resistance calculated by the standard and theoretical equation method, the end resistance increased by ring stiffeners should be considered in actual project. It is proposed that the calculation method considering the resistance reduction coefficient β can accurately predict the penetration resistance and the required differential pressure of bucket foundation with ring stiffeners, the recommended resistance reduction coefficient is 0.52 for the static penetration method, 0.33 for the undrained shear strength method, and 0.31 for the c and φ parameter method. The prediction of penetration resistance of thin-walled bucket foundation is the key to successful installation. In view of the problem that the resistance reduction effect of ring stiffeners is not considered in the existing calculation methods of penetration resistance, based on the field penetration date of thin-walled bucket foundation with ring stiffeners in an offshore wind farm and combined with the field installation situation, the resistance reduction effect of the angle iron ring stiffeners on the skin friction resistance was explored, and the influence of ring stiffeners on the end resistance was analyzed by the method of standard and theoretical equation, the calculation method of the penetration resistance considering the resistance reduction coefficient β was proposed. The following conclusions are obtained：•The existing specifications or methods do not consider the resistance reduction effect of the ring stiffeners when calculating the resistance of the bucket foundation with the ring stiffeners during the penetration process, resulting in the calculation results being larger than