Study On Driveability Of Super Large Diameter And Deep Penetration Pile In Offshore Paltform Foundation

Pile driving in offshore platform foundation is a synthetic,complex and systemic research involved subjects such as dynamics, structure mechanics and soil mechanics. Based on the data of pile driving records of a great number of piles in offshore platforms and the project about driveability analysis of super large diameter, super length, deep penetration pile of one oil-gas field in our South Sea,simultaneously, following up the front of the research of pile driving, studies have been performed as followings: 1. The stability of pile stick-up is usually ignored in practical engineering of pile driving. Numerical stimulation analysis for stability of pile stick-up with geometrical nonlinear 3-D finite element method (FEM) in pile foundations of offshore platform was performed. i.e., the effect of Linear and nonlinear analysis, the gradient of pile, the length of pile stick-up, and the horizontal force on the stability of pile stick-up were studied in details. 2. Based on the difference of deformation and failure mechanism for pile side soil and pile toe soil, soil mechanics theory, and results of laboratory experiments and field tests, hyperbolic model and ideal elastic-plastic model were proposed to describe the behavior of the soil adjacent to the pile shaft and the soil at the pile toe, respectively. And the hyperbolic model was established. 3. The soil plug has an important effect on the pile driveability, and the pile diameter has an important effect on the property of soil plug, too. Then the plugged effect judging method and nonlinear model of soil plug of the large ( super large ) diameter, super length, deep penetration pile have been established. Hyperbolic model of soil plug was also proposed to calculate the inside static resistance. And the mode of dynamic distribution of inside extreme static resistance was firstly proposed. 4. Based on the above hyperbolic model for the shaft soil and the soil plug, 1-D stress wave theory and Smith method, a program of analysis driving pile (ADP) wasdeveloped and applied in calculation of piling in several offshore platform foundation engineering. The results show that the program can be used to study on the large (super large), super length, deep penetration pile driveability and bearing capacity.5. The prediction analysis of pile driveability and bearing capacity in several projects was performed with the ADP program.