Accounting for stress-dependent stiffness of skirted circular foundation during monotonic loading in layered seabed

Calibration of Hardening Soil Model with Small-Strain Stiffness (HSsmall) for the centrifuge test of a laterally loaded suction caisson on a natural deposit of Yellow sea silty sand underlain by sandy silt is presented. The HSsmall model, in principle, consists of shear and compression hardening and is capable of simulating the stress-dependency of soil stiffness. A study site off the coast of Korea, so called Yellow sea, was selected as the reference prototype site which is considered to have great potential for future offshore wind farms. The study site seabed is composed of three layers of soil, of which only the top two layers are of interest. The top soil consists of a dense silty sand classified as SM and extends from the ground level to 11 m of depth. The second soil layer consists of a thick sandy silt from 11 m to 32 m of depth. Monotonic centrifuge test was performed on suction caisson having 15.5 m diameter and 10.5 m skirt length. Calibration of the HSsmall model was based on monotonic test data, drained triaxial tests, shear wave velocity measurements, CPT test data and empirical relationships for shear modulus at small strains.