Research On Capacities Of Four-compartment Suction Bucket Foundations On Soft Clay Under Combined Loading

With the fast development of our country's port and ocean engineering,high stability of the foundation has became more important.As a kind of foundations suitable for soft clay,suction bucket foundations have been widely used in design and construction of ocean platforms,wind turbines,breakwaters and so on.Four-compartment bucket foundations is a new type of foundations with cruciform internal skirts in the buckets,which can enhance the structure stiffness and ensure good perpendicular during floating transportation and sinking by controlling input and output of air or water of each compartment.But there are rare research on effect of internal skirts on capacity for three-dimensional bucket foundations.And for bucket-based breakwaters,previous researches did not involve effect of bucket spacing on foundation capacities.Foundations in real projects are not only subjected to the long-term effects of vertical loads caused by upper structure and their self-weight,but also environmental loads on the superstructure,such as waves,currents and winds.This makes the foundations subjected to combined vertical(V),horizontal(H)and moment(M)loading,so it is necessary to study the capacities of four-compartment suction bucket foundations under uniaxial and combined loading.In this dissertation,finite element models of single four-compartment bucket foundations and four-compartment bucket-based breakwaters were built to investigate uniaxial capacities and failure envelopes under VHM loading of this new type of foundations.The main contents are abstracted as follows:(1)For different soil heterogeneities ? and embedment ratios d/D,finite element models of single four-compartment bucket foundations were built to investigate the foundation capacities under uniaxial and combined loading.The effect of internal skirts on capacity for three-dimensional bucket foundations was studied by comparing the capacities of four-compartment bucket founfations,traditional bucket foundations and solid circular foundations.Considering the loading condition and structure feature of single four-compartment bucket founfations,effect of loding directions on unixial capacities was also discussed.(2)For ?=6,finite element models of four-compartment bucket-based breakwaters were bulit to study unixial capacities under different embedment ratios and buket spacings,and compare them with those of single four-compartment bucket founfations.For combined loading,effect of bucket spacing on failure envelopes was analysed.Finaly,to evaluate effect of soil heterogeneity,the unixial capacities and failure envelopes were also compared for under different ?..(3)Based on the finite element results for single four-compartment bucket foundations and four-compartment bucket-based breakwaters,approximating expressions of unixial capacities and failure envelopes were proposed for this two conditions respectively.These can be used to optimise foundation geometry for a given set of design loads and help applications of this new type of foundations.