The full-scale field-test on uplift behavior of pedestal piles with small extend angle enlarged base and normal straight-shafted piles has been carried out. It indicates that the uplift bearing capacity of former increases 50 percent than that of the latter. In order to know the contribution of enlarged base of pedestal pile

the composition of uplift resistance of enlarged base is analyzed by FEM. And the development of each elementary composition along with the uplift is studied. The sensitivity analysis is done for different diameters

lengths

expansion angles of enlarge base and soil characteristics in which enlarged base embedded respectively. The uplift mechanism of enlarged base is known by contrasting the result computed at different values of same parameter. Finally

some advices for design of pedestal piles with enlarged base are proposed by combination of theoretical analysis and practice.