Research on the Bearing Characteristics of Bucket Foundations for Offshore Wind Turbines in Double-Layered Clay

Abstract

Bucket foundations have been widely used in marine engineering, such as offshore wind power, due to their anti-overturning performance and convenient installation. In China’s coastal areas, clay soil is widely distributed, and most of the seabed has layered clay. However, the bearing capacity of bucket foundations in layered soil is significantly different from that in homogeneous soil. Currently, there is relatively little research on the bearing capacity of bucket foundations in layered clay. Therefore, the finite element analysis method is adopted to establish a bearing capacity calculation method of bucket foundations in double-layer clay. The axial failure mechanisms and ultimate bearing capacity of bucket foundations in double-layer clay are deeply discussed, and the corresponding ultimate bearing capacity calculation method is given based on the numerical analysis results. The combined bearing capacity of bucket foundations in double-layer clay is fully analyzed, and the evolution method of V-H, V-M, H-M, and V-H-M failure envelopes is given.

Keywords

Bucket foundation / Numerical analysis / Double-layered clay / Offshore wind power

Statement of the Use of Generative AI and AI-Assisted Technologies in the Writing Process

During the preparation of this manuscript, the author(s) used DeepSeek for linguistic polishing and academic expression optimization. After using this tool/service, the author(s) reviewed and edited the content as necessary and take full responsibility for the content of the published article.

Acknowledgments

The authors of this research are grateful for support funded by National Natural Science Foundation of China (No. 425022694) and Tianjin Science and Technology Project: Major Project for State Key laboratory (No. 25ZXZSSS00520).

Author Contributions

Conceptualization, J.W. and R.L.; Methodology, Y.F., H.Z. and J.W.; Software, H.Z. and Q.Z.; Validation, Y.F. and J.W.; Formal Analysis, Y.F. and X.W.; Investigation, Y.F. and H.Z.; Resources, J.W. and R.L.; Writing—Original Draft Preparation, Y.F. and X.W.; Writing—Review & Editing, J.W.; Visualization, Y.F. and Q.Z.; Supervision, R.L.; Funding Acquisition, X.W., Q.Z. and R.L.

Ethics Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The data presented in this study are available on reasonable request from the The data are not publicly available due to their large size and subsequent ongoing research

Funding

This research was funded by National Natural Science Foundation of China, grant number 42502269 and Tianjin Science and Technology Project: Major Project for State Key laboratory, grant number 25ZXZSSS00520.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this pape.

References

[1] Zavvar E, Rosa-Santos P, Taveira-Pinto F, Ghafoori E. Lifetime Extension of Offshore Support Structures of Wind Turbines: A Review. Renew. Sustain. Energy Rev. 2025, 217, 115788. DOI:10.1016/j.rser.2025.115788

[2] Zavvar E, Rosa-Santos P, Ghafoori E, Taveira-Pinto F. Analysis of Tubular Joints in Marine Structures: A Comprehensive Review. Mar. Struct. 2025, 99, 103702. DOI:10.1016/j.marstruc.2024.103702

[3] Cai Z, Fan K, Zhu X. Dynamic characteristics of offshore wind power with bucket foundation based on field tests. Chin. J. Geotech. Eng. 2025, 47, 443-452. DOI:10.11779/CJGE20231183

[4] Wang J. Research on the Multi-Dimensional Load-Bearing Capacity of Wide and Shallow Cylindrical Foundations for Offshore Wind Power in Clay Soil. Ph.D. Thesis, Tianjin University, Tianjin, China, 2021. https://d.wanfangdata.com.cn/thesis/D02721970 (accessed on 1 May 2021).

[5] Ma P. Research on the Interaction Between Cylinder and Soil under Static and Dynamic Loads of Tubular Foundations for Offshore Wind Turbines. Ph.D. Thesis, Tianjin University, Tianjin, China, 2019. Available online: https://d.wanfangdata.com.cn/thesis/D02022543 (accessed on 1 June 2019).

[6] Chen G. Limit Analysis and Experimental Research on Foundation Bearing Capacity of Wide-Shallow Tubular Foundations for Offshore Wind Turbines. Ph.D. Thesis, Tianjin University, Tianjin, China, 2014. Available online: https://d.wanfangdata.com.cn/thesis/D815411 (accessed on 1 December 2014).

[7] Gourvenec S, O’Loughlin CD. Drum Centrifuge Tests of Shallow Skirted Foundations on Soft Clay. In Proceedings of the Sixth International Conference on Physical Modelling in Geotechnics—6th ICPMG’06, Hong Kong, China, 4-6 August 2006; pp. 645-650.

[8] Mana DSK, Gourvenec SM, Randolph MF, Hossain MS. Failure mechanisms of skirted foundations in uplift and compression. Int. J. Phys. Model. Geotech. 2012, 12, 47-62. DOI:10.1680/ijpmg.11.00007

[9] Hung LC, Kim SR. Evaluation of vertical and horizontal bearing capacities of bucket foundations in clay. Ocean Eng. 2012, 52, 75-82. DOI:10.1016/j.oceaneng.2012.06.001

[10] Liu R, Yang C, Chen G. Bearing characteristics of bucket foundation based on lower bound method of limit analysis. Chin. J. Geotech. Eng. 2024, 46, 1573-1581. DOI:10.11779/CJGE20220703

[11] Wang J, Liu R, Chen G, Yang X. Upper Bound Solution Limit Analysis of Vertical Bearing Capacity of Shallow Bucket Foundation for Offshore Wind Turbines. Acta Energiae Solaris Sin. 2022, 43, 294-300. DOI:10.19912/j.0254-0096.tynxb.2021-0664

[12] Ding H, Zhang C, Zhang P, Zhai H. Effect of overlying soft soil layer on bearing capacity of four bucket foundation for offshore wind turbines. J. Harbin Eng. Univ. 2020, 41, 67-75. DOI:10.11990/jheu.201808055

[13] Lian J, Cao Z, Yang X, Li H. The anti-overturning bearing capacity of four-bucket foundation in clay with soft layers on top and hard layers at the bottom. Ocean Eng. 2024, 42, 1-10. DOI:10.16483/j.issn.1005-9865.2024.01.001

[14] Zhang P, Feng J, Li X, Zhang J, Yue C, Ding H. Influence of Different Soil on Horizontal Bearing Characteristics of Tripod Suction Jucket Foundations. Acta Energiae Solaris Sin. 2023, 44, 189-194. DOI:10.19912/j.0254-0096.tynxb.2022-0270

[15] Park JS, Park D. Vertical bearing capacity of bucket foundation in sand overlying clay. Ocean Eng. 2017, 134, 62-76. DOI:10.1016/j.oceaneng.2017.02.015

[16] Zhou M, Yang N, Tian Y, Zhang X. Inclined Pullout Capacity of Suction Anchors in Clay over Silty Sand. J. Geotech. Geoenviron. Eng. 2023, 149, 04023030. DOI:10.1061/JGGEFK.GTENG-11074

[17] Long C, Liang R, Zhou M, Li J, Zhang X. Inclined Pullout Capacity of Suction Anchors in Clay-Silty Sand-Clay Soil Deposits. Appl. Ocean. Res. 2025, 158, 104549. DOI:10.1016/j.apor.2025.104549

[18] Zhang Y, Chen Y, Li D, Hou X, Lai Y. Lateral Bearing Characteristics of Modified Suction Caisson Embedded in Layered Soil. Appl. Ocean. Res. 2025, 158, 104572. DOI:10.1016/j.apor.2025.104572

[19] Yu L, Liu J, Kong XJ, Hu Y. Three-dimensional large deformation FE analysis of square footings in two-layered clays. J. Geotech. Geoenviron. Eng. 2011, 137, 52-58. DOI:10.1061/(ASCE)GT.1943-5606.0000400

[20] Ma P, Qiu Y, Shu S. Numerical Simulation and Analysis of the Bearing Capacity of Suction Anchor in Layered Soils. Henan Sci. 2021, 39, 1264-1269. DOI:10.3969/j.issn.1004-3918.2021.08.011

[21] Wang W, Fu D, Yan Y, Zhou Z. Design Method of Geotechnical Capacity for Tripod Suction Bucket Foundations in Clay. Comput. Geotech. 2024, 169, 106171. DOI:10.1016/j.compgeo.2024.106171

[22] Skempton AW. The Pore-Pressure Coefficients A and B. Geotechnique 1954, 4, 143-147. DOI:10.1680/geot.1954.4.4.143

[23] Skempton AW, Bjerrum LJG. A Contribution to the Settlement Analysis of Foundations on Clay. Geotechnique 1957, 7, 168-178. DOI:10.1680/geot.1957.7.4.168

[24] Butterfîeld R, Houlsby GT, Gottardi G. Standardized sign conventions and notation for generally loaded foundations. Géotechnique 1997, 47, 1051-1054. DOI:10.1680/geot.1997.47.5.1051

[25] Fu D, Gaudin C, Tian Y, Cassidy MJ, Bienen B. Uniaxial capacities of skirted circular foundations in clay. J. Geotech. Geoenviron. Eng. 2017, 143, 04017022. DOI:10.1061/(ASCE)GT.1943-5606.0001685

[26] Vulpe C. Design method for the undrained capacity of skirted circular foundations under combined loading: Effect of deformable soil plug. Géotechnique 2015, 65, 669-683. DOI:10.1680/geot.14.P.200