Research Of Structural Performance Of Prestressed Concrete Pipe Pile And Development Of New Pile Type

Prestressed concrete pipe pile has several advantages, such as, high strength of pile body, high construction speed, easy quality assurance, energy saving, environmental protection and so on, so it has been used widely in many fields of urban and rural construction in our country, and what's more, it has been a large-scale used pile type in Tianjin. The research status quo and development trends of the prestressed concrete pipe pile at home and abroad are summarized in this paper. In order to solve some key problems, for instance, shear strength of prestressed concrete pipe pile, behavior of uplift pile under force, grouting to improve bearing capacity and so on, the following aspects of work have been done.In order to research the influence of stirrup reinforcement ratio, shear span ratio, concrete strength, effective prestress and reinforcement ratio of prestressed concrete pipe pile on its shear strength, special experiments of flexural bearing capacity and shear capacity have been carried out. Based on the analysis of experiment results and the structural theory of pipe pile under force, shear capacity calculation methods of pipe pile under different conditions are raised. This provides the basis for the design of pipe pile under horizontal force, and this can also supply references to seismic checking of pipe pile.Through special experiments of pile body, welding interface, joint strength to platform on piles and performance under static tension, the tensile bearing capacity of prestressed concrete pipe pile has been researched, and uplift bearing capacity and destructional forms of two ends, weld joint and pile body of prestressed concrete pipe pile as tensile structure have been quantitatively analyzed. Through theory analysis, it has been raised that the basic design principle of pipe pile as uplift pile and control node of uplift pipe pile.A kind of reamed grouting pipe pile that is suitable for soft soil area has been developed. Post grouting technology of bored concrete pile and grouting technology of mining area are introduced to pipe pile engineer. Using extended steel plate at the end of pile to ream pores makes grouting easily, and grouting makes the soil around pile, grout and pipe pile connected closely, so that compressive bearing capacity, tensile bearing capacity, lateral bearing capacity and aseismatic performance are all increased. Soil-pile interaction mechanism of reamed grouting pipe pile has been researched systematically, and for different bearing characteristics, appropriate grout ratio, grout pressure control standard and grout quantity are determined. Working mechanism of the increase of bearing capacity of pipe pile after grouting has also been researched. Systematic research that combines field testing with theory analysis can promote many aspects of work of pipe pile, like research development, design, technical service and so on. This research can make very good economic and social benefits, and it can also lay the foundation for the implementation of achievements of this project and technique extension.