The Analysis Of PHC Piple Pile’s Soil Compaction Effect

As a kind of pile with the characteristics of good economic benefit, short construction period, reliable quality, low environmental pollution, etc, PHC pipe piles are widely used in soft soil foundations. However, pipe pile foundation is relatively used less in the highway bridge pile foundation engineering, and its design theory has yet to be further in-depth study to facilitate popularization and application.Based on pile foundation project of the XuMing highway bridge, pile foundation project of Wuhu Second Yangtze River Bridge and some other pipe pile foundation projects in Hefei, the researches of compaction effect of PHC pile by theoretical analysis, field test and numerical calculation method are carried in this thesis. This thesis studied the compaction effect of the PHC pipe pile, analyses the main factors influencing the pipe pile soil compaction effect, discusses the effect of compaction on pile bearing capacity of single pile and deformation, etc. The main work as follows in this paper:1 、 Solving the displacement field and stress field in the process of construction by cavity expansion method. It can be concluded that in the elastic zone, the soil is pressed on the radial and tensioned on the tangential, stress reduced as a quadratic trend with the increase of distance to the pile center. And the formula showed that stress exponential decline with the increase of distance to the pile center in the plastic zone which radial in clay is 3-9d. Besides, soil’s displacement on the radial is less when the distance to the pile center is further.2、 Analysis of soil plugging effect and soil failure mode on the bottom of pile. Combined with the current research situation, soil plug formation process and status are studied by the Static equilibrium theory and the foundation bearing capacity theory in this paper; Soil failure mode on the bottom of pile is analyzed by the laboratory test, and the soil geotechnical parameters are measured to do the calculation of soil plug height. The research indicated that the state of soil plugging is related to wall friction, bearing capacity of foundation soil and the plug’s shear strength; soil plugging effect may closed when the pile is long and the height of plug is generally 10%～20% of the pile.3、 Numerical simulation analysis of compaction effect. Abaqus is used to simulate the process of driving pile in this paper. The factors are analyzed by changing the parameters of soil in the simulation and the law is summarized by setting different angles of the tone for the soil compaction effect in this paper. The research indicated that E influenced the stress most and the dilatation angle for the displacement The compaction displacement area is beyond 5～10d and stress in 10d.Besides, the tone angle influence the displacement and stress near the tone but has nothing to do with the displacement and stress along the shaft.4、 The vertical ultimate bearing capacity of single pile with considering the effects of soil compaction effect. Abaqus is used to simulate the process of pore pressure dissipation and static load test to analyze the influences of soil compaction effect to the vertical ultimate bearing capacity of single pile Based on the pile driving test and static load test in the field, semi-theoretical and semi-empirical formula of ultimate bearing capacity for single PHC pipe pile has been established with thinking about compaction effect.