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 degrees 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 degrees 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.

As an alternative to monopiles, suction bucket jacket foundations are gaining increasing popularity in China for supporting offshore wind turbines. One of the major design challenges and governing factors for foundation sizing is the long-term tilt caused by the differential settlement between the buckets due to a combination of prevailing wind directions and soft seabed conditions. The assessment of the long-term consolidation settlement is complicated and subjected to uncertainties, such as the load sharing between the skirt and the bucket lid, and load re-distribution with time as the soil response transits from short-term undrained behaviour to long-term drained behaviour. This paper presents an attempt to understand the short-term and long-term load sharing mechanisms for the suction bucket foundation by means of finite element analysis. Without modelling the large deformation installation process explicitly, the initial (undrained) load sharing mechanism and induced additional stress (or excess pore water pressure) in the soil body is first examined. The re-distribution of the load between the skirts and the lid as the excess pore pressures dissipate is subsequently investigated. The study examines a range of soil conditions and foundation aspect ratios. It is found that the undrained skirt wall friction capacity relative to the load level has an important impact on the initial load sharing mechanism. As consolidation takes place, significant load redistribution occurs, with the loads carried initially by the lid partially or fully transferred to the internal and external skirt wall frictions. The load sharing at completion of consolidation heavily depends on the drained skirt friction capacity relative to the load level. Guided by the numerical findings, a tentative analytical model for practical design purpose is proposed.