Study on p-y models for large-diameter pile foundation based on in-situ tests of offshore wind power

Large steel pipe pile is the most commonly used foundation structure for offshore wind power. However, the adopted design methods for large-diameter piles are p-y models, which are originally proposed based on many small-diameter pile tests for offshore oil and gas platforms. The prediction precision of the p-y models is relatively conservative, and its reliability is not clear. Thus, a modified p-y model for clay is proposed considering the influences of pile diameter and soil layer depth. Based on the data of in-situ pile tests of offshore wind power, the accuracies of p-y models for clay and sand recommended by the API code and modified p-y model for clay to predict the lateral soil resistance, pile deformation and bending moment of laterally loaded piles are analyzed and compared. The results show that the p-y model for clay recommended by the API code significantly overestimates the soil resistance of silt-sand and clay soil, and the predicted value using the p-y model for sand is about an order of magnitude higher than the measured one. The modified p-y model for clay can precisely predict the soil resistance of silt-sand and clay soil. Based on the modified p-y model for clay and p-y model sand proposed by Sorensen, the deformation and bending moment of piles in multi-layer seabed can be precisely predicted.