Laboratory tests on the frictional capacity of core pile – cemented soil interface

The pre-bored grouted planted (PGP) pile is a new type of composite pile, and the core PHC pile is surrounded by cemented soil layer. The frictional capacity of core PHC pile – cemented soil interface has a significant effect on the bearing capacity of PGP pile. A series of square pile (pipe pile) – soil interface shear tests were carried out in this study to study the frictional capacity of smooth square pile (pipe pile) – cemented soil interface. The shear test results show that the peak skin friction of square pile (pipe pile) – cemented soil interface both increased with the cemented soil strength; the peak skin friction of square pile – cemented soil interface was smaller than the peak skin friction of pipe pile – cemented soil interface of identical pile (equivalent) diameter, owing to the occurrence of stress concentration at the corners of square pile; the peak skin friction of square pile (pipe pile) – cemented soil interface both decreased with the pile (equivalent) diameter; the occurrence of cracks in the cemented soil caused the brittle failure of both square pile (pipe pile) – cemented soil interface.