Abstract: The advantage of high quality assurance rate and good compression resistance of PHC pipe pile can be exploited by using them in the foundation of retaining wall of embankments. It puts forward a new research about the connection mode between PHC pile and retaining wall base. Based on in-situ tests in Guang-Qing Expressway extension project, the mechanism of the connection between the base of retaining wall and PHC pile is studied. Two connecting mechanisms, one with cover plate, called the cushion type and the other without cover plate, called embedded type, are studied. The research suggests that both cushion type and embedded connection between PHC pile foundation soil bear the main load, embedded links between pile and pile soil stress are larger, which are about twice of the cushion type, bearing capacity rate difference of inside and outside the pile for embedded type is more apparently. Deflection of the retaining wall cannot be prevented with the cushion type connecting mechanism, as opposite to the embedded type, in which the wall can be kept in a stable state by the constraint resulting from the piles. For both connecting types, the base of the retaining wall bears tension force along the embankment direction and non zero-compression zones exist in this surface. There is very little difference in horizontal displacement for two connecting types, and the horizontal load is mainly carried by the soils around the piles.

Key words: retaining wall, PHC pipe pile, cushion type, embedded type, connection mode