Influence of Length to Diameter Ratio of the Skirt on Horizontal Bearing Characteristics of Tripod Suction Jacket Foundation in Sandy Soil

Abstract

The tripod foundation (TF) is a prevalent foundation configuration in contemporary engineering practices. In comparison to a single pile, TF comprised interconnected individual piles, resulting in enhanced bearing capacity and stability. A physical model test was conducted within a sandy soil foundation, systematically varying the length-to-diameter ratio of the TF. The investigation aimed to comprehend the impact of altering the height of the central bucket on the historical horizontal bearing capacity of the foundation in saturated sand. Additionally, the study scrutinized the historical consequences of soil pressure and pore water pressure surrounding the bucket throughout the loading process. The historical findings revealed a significant enhancement in the horizontal bearing capacity of the TF under undrained conditions. When subjected to a historical horizontal loading angle of 0° for a single pile, the multi-bucket foundation exhibited superior historical bearing capacity compared to a single-pile foundation experiencing a historical loading angle of 180° under pulling conditions. With each historical increment in bucket height from 150 mm to 350 mm in 100 mm intervals, the historical horizontal bearing capacity of the TF exhibited an approximately 75% increase relative to the 150 mm bucket height, indicating a proportional relationship. Importantly, the historical internal pore water pressure within the bucket foundation remained unaffected by drainage conditions during loading. Conversely, undrained conditions led to a historical elevation in pore water pressure at the lower side of the pressure bucket. Consequently, in practical engineering applications, the optimization of the historical bearing efficacy of the TF necessitated the historical closure of the valve atop the foundation to sustain internal negative pressure within the bucket. This historical measure served to augment the historical horizontal bearing capacity. Simultaneously, historical external loads, such as wind, waves, and currents, were directed towards any individual bucket within the TF for optimal historical performance.

Keywords

Offshore wind / Suction bucket jacket foundation / Horizontal bearing capacity / Vertical load / Soil pressure / Finite element model

References

[] Bang S, Cho Y (2002) Ultimate horizontal loading capacity of suction piles. International Journal of Offshore and Polar Engineering, 12(01)

[] Bang S, Jones KD, Kim KO, Kim YS, Cho Y. Inclined loading capacity of suction piles in sand. Ocean Engineering, 2011, 38(7): 915-924,

[] Byrne BW, Houlsby GT. Experimental investigations of response of suction caissons to transient vertical loading. Journal of Geotechnical and Geoenvironmental Engineering, 2002, 128: 926-939,

[] Cheng X, Wang J, Wang Z. Incremental elastoplastic fem for simulating the deformation process of suction caissons subjected to cyclic loads in soft clays. Applied Ocean Research, 2016, 59: 274-285,

[] Ding HY, Wang L, Zhang PY (2018) Study on the lateral bearing capacity of single-helix pile for offshore wind power: Proceedings of the ASME 37th International Conference on Ocean, Offshore and Arctic Engineering, Vol 9

[] Hirai H. Analysis of Cylindrical and Rectangular Bucket Foundations Subjected to Vertical and Lateral Loads in Sand Using a Three-Dimensional Displacement Approach. Soils and Foundations, 2020, 60(1): 45-62,

[] Hung LC, Kim S. Evaluation of combined horizontal-moment bearing capacities of tripod bucket foundations in undrained clay. Ocean Engineering, 2014, 85: 100-109,

[] Hung LC, Kim SR. Evaluation of vertical and horizontal bearing capacities of bucket foundations in clay. Ocean Engineering, 2012, 52: 75-82,

[] Kim D, Choo YW, Kim JH, Kim S, Kim DS. Investigation of monotonic and cyclic behavior of tripod suction bucket foundations for offshore wind towers using centrifuge modeling. Journal of Geotechnical and Geoenvironmental Engineering, 2014, 2014, 140: 4014008,

[] Liu MM, Lian JJ, Yang M. Experimental and numerical studies on lateral bearing capacity of bucket foundation in saturated sand. Ocean Engineering, 2017, 144: 14-20,

[] Liu SJ (2009) A Study on Bearing Capacity Behavior of Suction Multi-bucket Foundation for Offshore Wind Turbine. Dalian University of Technology

[] Liu YG, Ding HY, Zhang PY. Model tests on bearing capacity of composite bucket foundation in clay. Chinese Journal of Geotechnical Engineering, 2016, 38(12): 2315-2321

[] Mahmood MR, Fattah MY, Khalaf A. Experimental investigation on the bearing capacity of skirted foundations on submerged gypseous soil. Marine Georesources & Geotechnology, 2020, 38(10): 1151-1162,

[] Sun LQ, Qi YM, Feng XW, Liu ZQ (2020) Tensile capacity of offshore bucket foundations in clay. Ocean Engineering, 197. https://doi.org/10.1016/j.oceaneng.2019.106893

[] Yun G, Bransby MF. The undrained vertical bearing capacity of skirted foundations. Soils and Foundations, 2007, 47(3): 493-505,

[] Zhang P, Shi J, Ding H, Guo YH. Design of offshore wind power foundation with multi-bucket. Transactions of Tianjin University, 2016, 22(6): 502-507,

[] Zhao XL, Li YY, Wang X. Experimental study on horizontal bearing characteristics of tripod-bucket foundation in sand. Journal of Hunan University(Natural Sciences, 2021, 48(9): 20-29

[] Zhu B, Byrne BW, Houlsby GT. Long-term lateral cyclic response of suction caisson foundations in sand. Journal of Geotechnical and Geoenvironmental Engineering, 2013, 139: 73-83,

[] Zhu B, Zhang WL, Ying PP, Chen YM. Deflection-based bearing capacity of suction caisson foundations of offshore wind turbines. Journal of Geotechnical & Geoenvironmental Engineering, 2014, 140(5): 04014013,