EFFECT OF GRID STRENGTH ON PILE-SOIL STRESS RATIO OF PILE-NET COMPOSITE

This paper aims to explore the effects of different grille intensities to the variation of pile-soil stress ratio of pile-net composite foundations. On the basis of pile-net composite working mechanism foundation, it derives analytically the pile-soil stress ratio. Then it takes the net composite foundation of Ganlong(Ganzhou-Longyan) and Harbin-Dalian(Harbin-Dalian) high-speed rail piles as an engineering examples. It carries out a comparative analysis of the measured data from the pile under the grille strength 100kN·m^-1 and 300kN·m^-1 conditions to understand the pile-soil stress ratio variation. Finally it establishes a three-dimensional numerical model and further analyses the pile-soil stress ratio variation for the grid strength between 100kN·m^-1~400kN·m^-1. The results show that:as the grid strength increases from 100kN·m^-1 to 300kN·m^-1, the pile-soil stress ratio increased considerably. When the grid intensity exceeds 300kN·m^-1, the pile-soil stress ratio increases to a lesser extent. By considering the characteristics of the greatest contribution composite foundation bearing, it is recommended to select the grid strength 200kN·m^-1~300kN·m^-1. Under this condition, the pile-soil stress ratio is from 3.8 to 4.5.