The demand for high bearing capacity posed by compressive load and uplift load on foundation pile can
be addressed by pressure grouting. By conducting compressive test and uplift test on post-grouting piles, we studied the mechanism of load transfer on post-grouting piles, and compared the differences in side friction and bearing capacity of piles between compressive test and uplift test. We also identified the load transfer paths and the approaches of compressive force and uplift force in the failure process. Research result indicates that pressure grouting technology improves the bearing capacity of pile and the friction between pile and soil; moreover, a mechanical interaction is produced by pressure grouting, which also enhances the bearing capacity of pile, in particular, the uplift pile. The results offer reference for researches on improving the bearing capacity of uplift pile without increasing the pile length.