A limiting equilibrium method for calculating cyclic bearing capacities of suction anchors in soft clays using undrained cyclic shear strength of soft clays was developed based on the failure mode of suction anchors with inclined loads at the optimal loading point. Effects of average shear stresses due to average mooring loads on cyclic shear strengths of soft clays and cyclic bearing capacities of suction anchors were considered for the method. In order to verify its feasibility

a large number of model tests of suction anchors with combined average and cyclic mooring loads were conducted associated with different test parameters. The displacement criterion to failure at the loading point associated with the vertical pullout failure mode was determined based on test results. Cyclic bearing capacities of model tests with different parameters were determined based on the criterion. Cyclic bearing capacities associated with different model tests were further calculated by limiting equilibrium analyses using the relationship determined by undrained cyclic triaxial tests between normalized cyclic strengths and normalized average stresses and measuring shear strengths of model test strata. Comparison between calculating and testing results show that calculating results larger than testing results for the vertical pullout failure mode of suction anchors with taut mooring system. The average difference between them is 1.9%. Most of differences are not more than 10%. Therefore

it is appropriate that the calculating result is decreased 10% if the cyclic bearing capacity associated with the vertical pullout failure mode is calculated using the method for suction caissons with taut mooring system in soft clays.