不同排水条件下桶形基础上拔承载特性研究

Owing to its convenient installation and reusability, bucket foundations have been widely used in the ocean engineering field.Bucket foundations need resist considerable tensile loads during service or decommission, therefore, the accurate calculation of the uplift bearing capacity of bucket foundations is important for ensuring stable operation and facilitating future recycling. The uplift bearing capacity of offshore bucket foundations is related to the geometry of the foundation, uplift velocity, soil properties, and preloading owing to self-weight.In this paper, the finite-element method is employed to investigate the tensile capacity of bucket foundations.The failure mechanisms and variation in negative pressure are analyzed through the joint calculation of key factors, such as aspect ratio, uplift velocity, soil properties, and preloading. The normalized uplift velocity vs/C_v, where v denotes the uplift velocity, s represents the characteristic length of a drainage path, and C_v is the consolidation coefficient, is proposed to determine the drainage conditions of the bucket foundation uplift process. The calculation formulas of the tensile capacity of offshore bucket foundations under undrained and drained conditions are derived by considering the failure mechanisms and components of mobilized resistance. Further, a unique expression of uplift bearing capacity under the partial drainage condition is derived as a function of the length-to-diameter aspect ratio L/D, normalized loading velocity vs/C_v, and shear strength of a soil. An example application assisting the routine design of the engineers is included to demonstrate the proposed calculation procedure of uplift bearing capacity using the numerical results derived from the current study, which can be directly applied to the engineering design.