The Deformation Calculation Study Of Bucket Foundations In Soft Clay Under Cyclic Loads

Nowadays, bucket foundations have been applied more and more extensively in the offshore engineering due to their superiorities, but there is still not a good method to evaluate cyclic bearing capacities of bucket foundations in soft clay. In this paper the method by which cyclic accumulative deformations were equaled to creeps was studied to calculate deformations of bucket foundations in soft clay under cyclic loads, and bearing capacities were evaluated by deformation calculations.Firstly, failure characters of bucket foundations were studied by a series of bucket foundation model tests. The preparation of the soil tank, the penetration of model bucket and cyclic loading tests were introduced in this paper. Deformations of bucket foundations under static and cyclic loads were obtained by model tests, and results of tests showed that cyclic accumulative deformations were similar to creeps, which provided a reference to calculations of deformations.Secondly, the relationship between cyclic accumulative strains and their relative factors was established. In this paper unconsolidated undrained cyclic triaxial tests of the soil used in model tests were conducted under different static and cyclic loads to study characters of cyclic accumulative strains. And the relationship was established among strains, cyclic stresses, static stresses and the numbers of cycles.Finally, model tests were simulated using the finite element method, and deformations of bucket foundations under static and cyclic loads were calculated using the equivalent method. Deformations produced by different cyclic loads under same static loads at the same number of cycles were picked up from calculating results. Then cyclic bearing capacities were determined according to the certain failure criterion, and calculating results were compared with those of model tests to analyze the method's reasonability. It is feasible to calculate deformations of bucket foundations in soft clay under static and cyclic loads using this equivalent method, and cyclic bearing capacities of bucket foundations in soft clay could be well evaluated using this method.