As an important parameter of calculating the limit skin friction which is a main part of the ultimate uplift capacity of single piles in sand

the rationality of the coefficient of lateral earth pressure K will affect the accuracy of the ultimate uplift capacity of single piles. Firstly

based on the passive stress state of dense sand around uplift piles and the active stress state of loose sand around uplift piles

the coefficients of lateral earth pressure of different relative densities sand are derived considering the effects of the skin friction and the surface roughness of piles. Afterwards according to cylindrical shear failure mode

a method for predicting the ultimate uplift capacity of single piles in sand is obtained considering the development critical depth of unit skin friction. Lastly

the test results of uplift piles are analyzed by the present method and the predicted ultimate uplift capacity of single piles agree well with those measured values.