Firstly

the results of in-situ testing of Zhoushan National Oil Reserve Base improved by preloading combined with plastic drains is introduced. Base on the in-situ measured data

the change rules of settlement

settlement in layers

deep soil displacement

and excess pore water pressure on soft clay foundation under preloading is analyzed; and further study on consolidation effects according to the analysis of stress and strain

including the empirical coefficient m applicable for the base is gained by the strain analysis. Finally

the result shows that the good effect can be gained on the soft clay foundation treated by preloading combined with plastic drains.