English：

To clarify the bearing characteristics and load transfer mechanism of long and large pilefoundations in dense silty fine sand strata in the middle and lower reaches of the Yellow River, and toexplore the settlement characteristics of pressure⁃bearing piles under vertical cyclic loading, the staticload tests of three long and large drilled grouting piles were carried out by designing tension⁃compressionanchor method loading with reaction devices, and the settlement law of pile top and pile end under finitecyclic loading was studied by numerical simulation. The results indicate that the side friction resistanceand pile end resistance of large diameter and long bored piles are not synchronized, and the degree of pileside friction resistance is related to the pile top load, soil properties, buried depth, and pile foundationconstruction technology. The long pile foundation in dense fine sand stratum shows the characteristics of apure friction pile. When calculating the bearing capacity of a long and large pile foundation, the surveyreport parameters based on the standard value should be multiplied by the corresponding correctioncoefficient. The side friction resistance of the pile body in the dense silty fine sand layer is not fullyutilized. The finite loading and unloading of the permanent⁃temporary combination beam yard cannotcause obvious deformation of the pile foundation, and the influence of the beam yard operation on thebearing capacity of the pile foundation is weak.