Field Tests And Numerical Modelling On Bearing Capacity Of Prestressed Concrete Pipe Piles

Prestressed concrete pipe pile is of high bearing capacity, steady quality, and low price, fast constrcution and so on. Now it has been widely used in the industry, civil construction, railway, high-way, bridge, haven, dock engineering projects. But the construction and soil-pile interaction, which affected and controlled the bear capacity of prestressed concrete pipe pile, are much complicated factors. Now there is no an ideal issue for the bearing capacity of prestressed concrete pipe piles. Consequently, the research on field test and numerical modeling on bearing capacity of prestressed concrete pipe pile is great significance for improvement of the design of bearing capacity prestressed concrete pipe pile.Based on the methods of effective stress analysis and field static loading tests, the characters of vertical and horizontal bearing loading of prestressed concrete pipe piles are discussed in this dissertation. The numerical modeling using the geotechnical engineering software FlipGenCN, combined with a practical example, was constructed and used to investigate the mechanism. Moreover, the soil-pile interaction is investigated under the self-weight and static loading. The following results are reached.(1) The settlements at pile top of prestressed concrete pipe piles increase with the value of vertical static loading.(2) The bending moments of pile increase with the level of lateral static loading. The values of bending moment firstly increase with the buried depth. Then they decrease with the buried depth. The Min value of bending moment is at the pile end.(3) The pile-soil relative displacement difference general increases with the level of lateral static loading. The Max value is at soil surface. But in the model using the linear beam element for pile, the soil-pile relative displacement from -12m to -17m of buried depth is almost zero. While in the model using the nonlinear beam element, the buried depth, at which the soil-pile relative displacement differences is almost zero, is from the pile end to -8m buried depth.(4) The results from filed tests and numerical simulations show that there are good agreements with each other. And results from the non-linear beam model is more objective and ration than those form the linear beam model. It is concluded that the numerical modeling using multiple spring model is capable of capturing the characteristics of bearing capacity of prestressed concrete pipe piles subjected to static loading, and effective and feasible. The selection of linear beam model can match the engineering need when the deformations of pile and soil are in the elastic state.The results of research and relational conclusion will perfect the analysis theory of prestressed concrete pipe piles, and provide references for the designs of similar engineering projects.