Analysis On Uplift Capacity Of Enlarged-bottom Piles

The enlarged bottom pile is a type of special figure pile. It is based on the straight pile, squeezed soil around the bottom of the pile with a hydraulic squeezed machine. Because of the higher bearing capacity, the enlarged bottom piles are widely used in recent years, such as the use in the power transmission towers and substructure.Up to now, the theory researches of piles with enlarged bottom can't keep up with the level of application. The tradition measures of ensuring vertical bearing capacity of piles with enlarged bottom are the field loading tests. But it costs too much time and funds, and also difficult to gain the whole Q-S curve. So it is necessary to discuss the bearing character of the enlarged bottom piles and find out a more reasonable method of numerical simulation to ensure vertical bearing capacity of the pile.In this paper, the FEM software ANSYS is used to model the pile-soil interaction and in-depth analyze bearing character of the enlarged bottom pile. The main research contents in this paper are as follows:(1)With the plane element, the axisymmetric model is established by ANSYS software, in witch, the contact elements are set between the pile and soil to simulate the separation and sliding. And then simulate the working mechanism of the pile under uplifting load.(2)The mechanics mechanism of enlarged bottom piles, the load transmission behavior and the failure mechanism of soil are analyzed. Then main factors affecting the bearing capacity and the uplift mechanism of pile in different kinds of soil are discussed.(3)3-D FEM model including the contact elements between the pile and soil of enlarged bottom piles in complex load cases.are established to analyze the bearing capacity. the load transmission behavior and the deformation of soil are analyzed in complex load cases.