Method for determining vertical bearing capacity of pile foundation by adopting small displacement loading

The invention belongs to the technical field of bridgework and in particularly relates to a method for determining the vertical bearing capacity of a pile foundation by adopting small displacement loading. The method comprises the following steps: (A), dividing the pile foundation into a plurality of sections and establishing a pile-earth calculation model; (B) loading a bridge pier according to the maximum end reaction of a bridge or the maximum allowed loading capacity of a bridge floor to obtain a loaded load P and a settling volume S; (C) arbitrarily taking a p value and calculating the loaded load P and the settling volume S corresponding to the p value; (D) unceasingly adjusting the p value through comparing P /S with P/S; (E), determining q value according to the final p value so as to determine the load transmission parameters of all pile sections; (F) drawing a pile-earth P-S curve; and (H) determining ultimate bearing capacity of the pile foundation. As the pile foundation bears different force in different soil layers, the pile foundation is divided into a plurality of sections to ensure the accuracy of model establishment, and proper p value is obtained through unceasing cyclical trial. As a result, the obtained P-S curve is particularly close to the actual P-S curve, and the finally measured ultimate bearing capacity of the pile foundation is extremely high in accuracy.