Transient vertical loading of model suction caissons in a pressure chamber

Vertical monotonic and cyclic loading tests on model suction caissons have been carried out to explore conditions relevant to the design of multiple-footing foundations for offshore wind turbines. The tests were conducted in a pressurised chamber, which simulates up to 20 m of water depth, to investigate the effect of cavitation on the ultimate tensile response of the caisson. Cyclic loading tests were also conducted at elevated pressures. Data from cyclic tests are presented to compare the response of caissons subjected to varying ambient pressures and rates of loading. The ambient pressure had little effect on the cyclic response. Faster rates of loading generated larger pressures beneath the lid of the caisson and increased the load−displacement stiffness. The ultimate tensile capacity was significantly affected by the ambient pressure and rate of loading. Implications for the design of offshore caisson foundations are discussed.