Evaluation of Soil–Foundation–Structure Interaction for Large Diameter Monopile Foundation Focusing on Lateral Cyclic Loading

Abstract

In this study, the monotonic and cyclic behavior of an offshore wind turbine with a monopile foundation installed in a sand layer were evaluated in the centrifuge. A simplified offshore wind turbine was modeled, and the lateral load was applied to the tower under displacement control. The monotonic loading test evaluated ultimate lateral load capacity and bending moment profiles under different loading levels. During cyclic loading, variations of moment-rotation responses, cyclic stiffness, and bending moments along the pile were observed. The initial rotational stiffness of the monopile decreased as the loading level increased. In the fatigue limit state (FLS) and service limit state (SLS) loading conditions, no noticeable variation in stiffness was observed with the number of cycles. However, in the ultimate limit state (ULS), the stiffness of the monopile increased during the first few cycles, followed by a decreasing rate of increase, and reached a certain value. The loading rate had a weakening effect on the monopile–soil interaction, which was supported by the bending moments induced in the monopile.

Bearing Characteristics of Tripod Bucket Foundation under Horizontal and Moment Load in Sand

“…Table 4 shows the moment capacity of the tripod bucket foundation calculated by FE analysis and Equation (1), in which M 0_FE is the moment capacity from FE analyses, and M 0_cal is the calculated moment capacity using Equation (1) proposed in this study. According to the comparison results, the error was within 10%.…”

“…Offshore wind energy has been developing rapidly in recent years as a clean and sustainable energy resource [1,2]. However, the construction expense, especially the cost of the foundation, negatively affects the cost-effectiveness of offshore wind farms.…”

A Study on the Lateral Load Capacity of a Novel Hybrid Monopile via a Centrifuge Model Test

“…Various foundation structures have been proposed to stably support offshore wind power structures. Among these, large-diameter monopiles are foundation structures with diameters of 4-8 m that have been most widely used for the foundations of offshore wind power installations due to advanced design technology and extensive experience Energies 2023, 16, 7234 2 of 21 in constructing monopoles in various soil layers [2][3][4][5][6]. They are typically installed on the seabed using a driving method in waters with a depth of less than 30 m. However, it remains a challenge to design and install monopiles in waters where silt layers or soft clay layers are widely distributed, such as in the West Sea of Korea, with few cases reported [7,8].…”