Large-scale penetration model tests of bucket foundations of different structural types in clay

Abstract

Clarifying penetration characteristics and accurately predicting penetration resistance of bucket foundations is crucial to ensure their smooth penetration. This study performed large-scale model tests on nearshore seven-compartment (SC) bucket foundations and novel deep-sea five-connected (FC) bucket foundations to systematically explore the penetration attitude, development of soil plugs, flow rates, bucket-soil interactions, and required suction of these two structures in clay. The good penetrability was identified for the new FC bucket foundation. The development of soil plugs due to bucket wall replacement as well as the mechanism of drag reduction of the inner wall and bucket end were revealed. The experiments demonstrated that the penetration flow rate was almost equal to the volume of bucket body entering the soil and accounted for approximately 95% of the total flow rate. A formula for calculating penetration resistance in clay that considers the effect of suction on the reduction in resistance of the inner wall and bucket end was proposed and validated by field tests. The research results improve the safety of bucket foundation penetration in clay and provide significant guidance for the installation of deep-sea FC bucket foundations.