3-D Non-linear FEM Study Of Composite Pile Foundation Under Vertical Loads

Because of taking load bearing capacity of soils under caps of composite pile foundation into consideration and decreasing the pile amount significantly, therefore, good economic benefit can be obtained by adopting composite pile foundation. Although many experts have done lots of researches on the design theories and calculation methods of composite pile foundation the design theories and calculation methods of composite pile foundation aren't accredited completely. So the mechanism of the pile soil interaction and mechanical properties is being a hot research realm.The pile-soil-raft interaction and the mechanical behaviors of composite pile foundation are studied in this article by three dimensional non-linear finite element methods. The main contents are given as follow:Analysis theories and calculation methods on composite pile foundation and its engineering application are introduced and summarized.The effect of variation of load, length of pile, distance between piles, diameter of pile and elastic modulus of soil on working properties of composite pile foundation was studied respectively by 3D plastoelastic FEM calculation based on a typical model. The characteristics of settlement of foundation, differential settlement of foundation, side friction of pile, pile-soil-load ratio and additional vertical stress in subsoil are described.An engineering project designed by composite pile foundation theory was studied by 3-D plastoelastic FEM. The reliability of the 3-D plastoelastic FEM. for calculating the composite pile foundation are also proved from the comparison between the results of the FEM calculation and that of the observation dataA case of the same engineering project designed according to the traditional design theory was also studied by 3-D plastoelastic FEM., the differences of results obtained from traditional pile foundation and composite pile foundation are compared and some valuable suggestion are given.