Study On A Set Of Techniques Of Prestressed Concrete Pipe Pile

Prestressed concrete pipe pile which is widely used in the recent decade is a type of precast concrete pile. This type of pile has many advantages, such as simple technique, better quality, low cost and convenient detection, so it has been widely used in geotechnical engineering. Though with the above merits, its squeezing effect and soil plugging effect of pile driving still need to be further researched, and its design theory and construction technique need to be further perfected. So the study on prestressed concrete pipe pile is of great theoretical and practical significance. Firstly, the results of both experimental and theoretical investigation of the squeezing effect are introduced. Moreover several methods commonly used in analyzing squeezing effect are discussed. Especially, the cylindrical cavity expansion theory is introduced in detail, and the advantages and disadvantages of these methods are presented. Then the soil plugging effect of prestressed concrete pipe pile are discussed. Based on the soil plugging effect, the cylindrical expansion model is established. Based on the assumption that the volume of soil squeezed out during the pile driving is equal to the deformation volume of soil around pile and the volume of soil plug, the analytical solutions of stress field, strain field, displacement field and the final expansive pressure are obtained. Secondly, the bearing capacity of pile is numerically simulated by ANSYS. The appropriate model of soil around the pile is established to analyze the static load test. After being properly meshed, displacement constraints are applied to the model then the solution is achieved. While defining the material properties, the Drucker-Prager model is used for the soil around the pile. In the end, the colored contours of deformation and stress are plotted, from which the rules of deformation and stress in both X and Y directions are concluded. Moreover, the parameters such as the diameter of pile, the length of pile and the type of soil are changed to simulate the static load test, then the three kinds of Q~s curve are plotted, and the conclusion about the rules of the bearing capacity of pile are drawn. Finally, the issues which exist in the design of the prestressed concrete pipe pile are discussed, and the reasons are also discussed. Meanwhile the design method, the construction techniques and the quality detection of the prestressed concrete pipe pile are introduced. This thesis promotes the research on work mechanism and design theory of prestressed concrete pipe pile, so it is of important theoretical and practical significance.