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.