Studies On Bearing Capacity Of Compaction Piles With Branches And Plates Based On Particle Flow Code In 2 Dimensions Theory

Compaction pile with expanded branches and plates is a new type of pile, which is developed from normal bored pile. The pile use different parts of hard soil besides itself to install branches and plates, and make friction pile variable cross-section multi-supports frication & end-bearing pile. The brahches and plates change the stress mechanism of the pile, and make bearing capacity improved while settlement deformation decreased. The foreign and domestic have much research about the bearing capacity of compaction pile with expanded branches and plates, such as in-situ tests, laboratory experiment, theory method and numerical simulation. This paper uses numerical simulation and finally compares with laboratory experiment.In the field of numerical simulation, the methods of research on pile with expanded branches and plates are all finite element methods or finite difference methods, which are based on the suppose of continuum models. While the basic nature of the interreaction between pile with expanded branches and the soil hangs on the deeply research on the mechanical characteristics in the field of mesoscopic of soil material, also hangs on the research on the relationship of mesoscopic structure and macroscopical mechanics phenomena. And so, this paper uses PFC2D based on the discrete element method to study the bearing capacity of compaction pile with expanded branches and plates.Pile with expanded branches and plates is simulated with PFC2D firstly. Using PFC2D, timestep-displacement of the pile, position of particles, contact force of particles and displacement of particles are studied, and the conclusion is:1. There exists"arch"in the upside of plates of pile during loading, and there are"cutting area"besides pile, which is closing pile during loading.2. The bearing capacity of pile with expanded branches and plates is composed mainly of the counterforce of underside plates and base of pile.The contrast between pile with expanded branches and plates and equivalent-diameter pile is studied secondly, and using PFC2D, the phenomena that the bearing capacity of pile with expanded branches and plates being higher and the anti-settlement deformation being lower than equivalent-diameter pile is explained through the analysis in the field of mesoscopic, and the conclusion is:1. Soil area affected by pile with expanded branches and plates is much bigger than equivalent-diameter pile during loading.2. The underside plates and base of pile give the great mass of bearing capacity for pile with expanded branches and plates, while the pile-side soil and base of pile give the great mass of bearing capacity for equivalent-diameter pile.3. Contrasting two kinds of pile, and finally found that the bearing capacity of pile with expanded branches and plates is higher and the anti-settlement deformation is lower than equivalent-diameter pile.The contrast between laboratory experiment and numerical simulation is studied lastly, and find many sameness in their performance, and so PFC2D could do some qualitative analysis for practical project.