REVIEW OF UPLIFT CAPACITY AND PULLOUT MECHANISM OF SUCTION CAISSONS FOR OFFSHORE FOUNDATION

The suction caisson is a new type of foundation having advantages such as easy construction,reuse and low cost. It has been successfully applied to offshore platforms and offshore wind turbines. Uplift capacity is the key factor in design of suction caissons used to fix the floating offshore platforms in deep water. Moreover,offshore wind farms should be updated with increasing the diameter of the wind turbine blades and the tower height,thus the existing foundation is not available to meet new design requirements. From the perspective of sustainable development,pullout and reuse of suction caissons are gradually attracting more attention. This paper presents an overview of the researches on uplift capacity and pullout characteristics of suction caissons,and also discusses the influencing factors of pullout capacity in the aspects of loading rate and soil properties. Investigations from the literature show that pumping water into suction caissons can cause seepage failure in sand,splitting failure in clay,and at this time the caissons cannot continue to be pulled out. It is recommended to be extracted by pullout loading or vibrating.