Numerical Investigation on Lateral Bearing Behaviour of a Cable-Reinforced Monopile System for Life-Extension of Offshore Wind Turbines in Clay
Xinyue Ma1, Zechao Zhang2, Canhui Li1, Xiao Lu1, Le Wang1,*, Run Liu1
1 School of Civil Engineering, Tianjin University, Tianjin, China
2 Science and Technology Research Institute, China Three Gorges Corporation, Beijing, China
* Corresponding Author: Le Wang. Email: 
(This article belongs to the Special Issue: Selected Papers from the 10th International Conference on Civil Construction and Structural Engineering (I3CSE 2026))
Structural Durability & Health Monitoring https://doi.org/10.32604/sdhm.2026.086791
Received 05 June 2026; Accepted 18 August 2026; Published online 10 September 2026
Abstract
Life-extension assessment and reinforcement of in-service monopile foundations are becoming increasingly important as early offshore wind farms approach the middle and late stages of their design lives. To improve the lateral bearing performance of existing monopiles without dismantling the original foundation, this study proposes a cable-reinforced composite system composed of a main monopile, auxiliary piles, and steel cables. A three-dimensional finite element model of a 3.0 MW offshore wind turbine monopile foundation in homogeneous clay was developed using ABAQUS, and the influences of load application angle, auxiliary pile diameter, auxiliary pile length, cable-to-vertical angle, and auxiliary pile number were investigated by a control-variable method. The unreinforced monopile has a baseline lateral bearing capacity of 11.88 MN at a mudline displacement of 0.1
D, where
D is the monopile diameter. For the three-auxiliary-pile configuration with a 1.5 m auxiliary pile diameter, a 15 m auxiliary pile length, and a 45° cable-to-vertical angle, the capacity reaches 13.65–14.14 MN under different load directions, corresponding to an improvement of 14.91%–19.08%. Increasing the auxiliary pile diameter from 1.0 to 2.0 m raises the capacity under the unfavorable 30° load direction from 13.19 to 14.17 MN, while increasing the auxiliary pile length from 10 to 25 m improves the capacity from 13.11 to 14.94 MN. Increasing the cable-to-vertical angle from 30° to 60° further increases the capacity from 12.92 to 14.66 MN. The four-auxiliary-pile system provides the highest reinforcement efficiency, with a bearing capacity of 14.85–15.61 MN and an improvement ratio of 25.06%–31.41%. In all cases, the maximum cable stress is below 251.4 MPa, far lower than the allowable limit of 1200 MPa. These results indicate that the proposed cable-auxiliary-pile system can effectively enhance the lateral resistance and service-life extension potential of offshore wind monopile foundations.
Keywords
Offshore wind power; monopile foundation; life extension and reinforcement; cable structure; lateral bearing capacity; finite element analysis
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