Experimental and numerical study on the static lateral performance of monopile and hybrid pile foundation

Considering the limitations of conventional monopiles in supporting the new generation of offshore wind turbines (OWTs), the idea of hybrid pile foundation has been proposed and studied in recent years. In this paper, static lateral load tests are conducted on model piles and hybrid pile foundations in saturated sand. The influence of pile stiffness and hybrid foundation type on the lateral response is analyzed. Three-dimensional (3D) coupled discrete continuum modelling is further performed to reveal the interaction mechanism between different pile foundations and the surrounding soil. Experimental results indicate that the lateral capacity of the hybrid pile foundation can be notably improved compared with that of the monopile foundation, especially at small pile displacement. And the lateral load response of the hybrid pile foundation is comparable to that of the monopile at the ultimate limit state. From a numerical perspective, the load transfer mechanism of different pile foundations is studied by analyzing the displacement pattern of pile and soil foundation and the distribution trend of horizontal soil stress. It reveals that the existence of footing and bucket foundation could improve the efficiency of soil resistance mobilization at shallow depth. The experimental and numerical study is expected to provide some new perspectives on the understanding of the lateral bearing characteristics of hybrid pile foundations.