Behavior Of Pile-Soil Interaction Under Vertical Load

Using pile foundation in building structures can significantly increase the bearing capacity, reduce the settlement and improve the seismic performance. But it is very hard to find the ultimate bearing capacity of pile in actual project and there are still many problems unsolved in characteristics of nonlinear contact between pile and soil and load transfer among pile, soil and structure. In the presented thesis, finite element limit equilibrium method (FELEM) of slope engineering is extended into analysis of ultimate bearing capacity and stability of interaction between pile and soil. Dynamic characteristic among pile, soil and structure is studied by using numerical method.The work of this thesis includes the following three parts:(1) Stability of slope and shallow foundation is estimated by using the FELEM. Safety factor and the most dangerous sliding surface of slope and shallow foundation obtained by using this method are verified by comparing with those from strength reduction finite element method and Prandtl"s theoretical solution.(2) Two-dimensional axisymmetric finite element model including nonlinear contact between pile and soil is constructed on the platform of ABAQUS. The ultimate bearing capacity of pile is calculated by using the load-settlement curve under vertical load. The influence of side friction of pile is considered. Then, the numerical results are used to verify the theoretical solution of load-settlement curve obtained by using the iterative computation and load transfer method with hyperbolic load transfer function between pile and soil. The reliability of the theoretical solution is confirmed. Safety factor and the most dangerous sliding surface are calculated by using FELEM in structural analysis of pile and soil.(3) Two-dimensional finite element model is constructed on the platform of ANSYS for dynamic structural analysis of interaction among pile, soil and structure. Natural frequencies, modes, displacements and shear of structure are calculated to study the effects of interaction among pile, soil and structure.