Study Of Uplift Capacity Of Caisson Foundations Under Different Drainage Conditions

The suction caisson is widely used in ocean engineering.On account of its special structure form,the suction caisson can not only bear downward load but also provide uplift bearing capacity,the uplift bearing capacity depends on drainage conditions.Negative pore pressure can be generated during uplift.According to the dissipation of negative pore pressure,we can consider the uplift is under undrained,partially drained and fully drained condition.The pull out rate,foundation size and coefficient of consolidation are considered and numerical methods are adopt to imitate the suction caisson uplift problem.Different bearing characteristics under different normalized uplift velocity is investigated and the method to calculate uplift bearing capacity is presented.Specific research contents and results are as follows:(1)By finite element software ABAQUS,the numerical model is set up to simulate the different L/D suction caisson under drainage conditions,bearing capacity and broken model in different drainage conditions are studied.(2)This paper summarizes the calculate method of uplift capacity under undrained and fully drained condition.The relationship between the pull out rate,foundation size and drainage conditions are presented.Considering uplift velocity,length-diameter ratio,soil strength and coefficient of consolidation the calculation method of partly drained uplift bearing capacity is proposed.(3)The effect of consolidation under preload is studied and the calculation method of uplift bearing capacity after consolidation under preload is proposed.(4)The bearing capacity of homogeneous soil and heterogeneous soil is calculated,and the effect of soil strength distribution on drainage condition is studied.