Finite Element Simulation And Bearing Capacity Analysis Of Cast-in-situ Piles With Expanded Branches And Plates

Cast-in-situ pile with expanded branches and plates which was developed on the basis of constant section bored pile is a new type of pile. The outstanding points of this kind of pile are both higher bearing capacity and lower displacement than the pile with constant section on the same conditions, offering both well economic and social benefits. Much attention have been paid on the bearing capacity property under lateral load or vertical load. In fact ,overwhelming piles foundation work under both lateral and vertical load at the same time, especially in ocean engineering and bridge engineering. This paper makes the numerical simulation of the bearing capacity property of the cast-in-situ pile with expanded branches and plates by using the ANSYS software ,making overall analysis of working property under only lateral load and vertical load. Much analysis on the bearing capacity property have been made in this paper.The main original work includes:First, by using ANASYS software, the three-dimension finite element models of the cast-in-situ pile with expanded branches and plates and the pile with constant section were developed, and the rational bearing capacity programs have been designed which are needed in the analysis of this paper. In the calculation, the linear elastic model is chosen to consider the pile material, and the D-P model is chosen to consider the soil around the pile. The surface-surface contacting element was adopted to consider the gap and sliding distance between pile and soil interface.Secondly, based on the results of 3-D finite element analysis of the cast-in-suit pile with expanded branches and plates and the pile with constant section under only lateral load and vertical load, some numerical conclusions can be developed. They include : as a result of branches with larger section than pile section are placed at proper location of pile, which can exert pre-punch load on the soil around the pile body, higher bearing capacity and lower displacement are offered by cast-in-situ pile with expanded branches and plates than pile with constant section.When branches and plates were placed closer ground ,or the distance between branches is one times the diameter of the branches, the lateral load capacity of pile with expanded branches and plates is larger than other distance between branches.Thirdly, analysis on the first stress field ,the third stress field ,vertical shear stress field and displacement field of the pile with expanded branches and plates and the pile with constant section under vertical load and lateral load were made.Related comparing analysis on principal stress field and displacement field of the pile with expanded branches and plates and the pile with constant section were also made.On the basis of the results of finite element simulation,the analysis on stress property at the early process of load exerted to the two branches which belong to the model of the pile with expanded branches and plates designed by this paper were made ,some law on stress distribution of the branches were developed.Furthermore ,by comparing analysis on stress field of soil around the pile with expanded branches and plates and the pile with constant section, some law about the developing process of plastic area of soil around the pile were developed.At last, by comparing analysis of the distributions of stress and displacement of the cast-in-suit pile with expanded branches and plates and the pile with constant section with contacting element and without it ,we found that the model with contacting element is better.BY comparing analysis on gap ,sliding distance and contacting stress of contacting element of the cast-in-suit pile with expanded branches and plates and the pile with constant section ,the results show that gap and sliding distance of the cast-in-suit pile with expanded branches and plates are fewer than the pile with constant section under lateral load.