Installation of suction caissons in calcareous silt

Design methods with parameters for clay were found to be not applicable for assessing installation resistance of stiffened caissons in calcareous silt. A series of centrifuge tests were carried out for investigating installation of a stiffened caisson in calcareous silt. The results from current and existing centrifuge tests on installation of unstiffened and stiffened caissons in calcareous silt have been assembled. A conventional shear resistance method has been extended accounting for the effects of inner ring stiffeners and strain rate dependency of the undrained shear strength. Contrary to current understanding, not all ring stiffeners provided end bearing resistance and not all the surfaces of the inner skirt contributed to interface frictional resistance. Friction factors for inner and outer skirt-soil interface frictional resistance were different and affected by the sensitivity of the soil. A more informed design expression was proposed and calibrated against the measured data. Improved estimations were obtained for (i) outer skirt-soil interface friction factor, (ii) inner skirt-soil interface friction factor, (ii) strain rate effect, (iii) softening effect, (iv) skirt tip end bearing factor, and (vi) bottom stiffener end bearing factor. A set of suggested parameters for calcareous silt and clay are compared and tabulated for application in practice.