Overlength piles have been found abroad application to large bridges and high buildings. Based on an example of an over- length pile foundation

the influences of base strata on the behavior of overlength piles are studied with 3D FEM. Duncan-Chang elastic model is used to simulate the constitutive relation of soils; and linear elastic model is used to simulate the constitutive relation of concrete and rock. Results of analyses indicate that for the different base strata

the scales of tip resistance and side resistance are different

but the behaviors are same; the critical loads are different

but the limit displacements are almost same; the tip resistances are different

but the failure reasons are shearing failure of the soils around piles.