The post-grouting technology could improve the bearing capacity of bored cast-in-place piles; and the reinforcing mechanism of the post-grouting technology differs in different soil strata. In soft soils
the improvement of bearing capacity of long piles is mainly derived from increase in frictional resistance. The testing results of static loads and shaft stress are analyzed; and the relationships between frictional resistance and relative displacement are revised in consideration of deformation caused by soil continuity; and they are fitted by transfer functions. Based on transfer functions
the ultimate values of frictional resistance are calculated so as to reflect the real distribution regulations of frictional resistance along the shaft .