Analysis on response prediction of a single pile and pile groups based on the Runge-Kutta method

The conventional load-transfer approach can not consider the interaction of piles, and can not be directly used in the analysis of the response of pile groups. The interactive effects among piles can be taken into account in the shear displacement method based on the principle of superposition. In the present analysis, the shaft displacement of a single pile at a given depth is assumed to be composed of the pile-soil relative displacement developed at the disturbed soil around pile and the elastic vertical soil displacement developed in the soil mass. A new load-transfer function which is very similar to a hyperbolic model is then established to describe the relationship between unit skin friction and shaft displacement at a given depth. Furthermore, a hyperbolic model is used to simulate the relationship between unit end resistance and pile end displacement. As to the analysis of the response of pile groups, the interactive effects among piles are considered by using the shear displacement method. For an individual pile in pile groups, new load-transfer functions are established to capture the relationship between unit skin friction and shaft displacement and the relationship between end resistance and pile end displacement. Based on the fourth order Runge-Kutta method, a modified load-transfer method is proposed to analyze the response of pile groups considering the interactive effects among piles. The reliability of the present method is checked by using comparisons of the present calculated results, the measured results and the computed values derived from other methods.