Theoretical calculation on ultimate bearing capacity of helical piles under tension

A failure model with undetermined parameter N considering pile type and soil parameters was proposed under shallow buried condition. The specific failure surface form was determined by the derivative of the parameters to obtain the ultimate vertical uplift bearing capacity; the ellipsoidal failure model was proposed under the deep buried condition, and the ultimate uplift bearing capacity was solved based on the limit equilibrium principle. Besides, the vertical uplift model test of single screw pile in sandy soil foundation was carried out. The results show that the earth pressure above the upper anchor plate of double anchor screw pile (s/D=1.36) increases with the increase of load; the earth pressure above the lower anchor plate decreases with the increase of load, and tends to be stable when the soil reaches the plastic stage. The accuracy and reliability of the theoretical calculation model established in this paper are verified by comparing the test results of the existing literature and the theoretical calculation methods of the existing literature with the model test results of this paper. © 2021, Central South University Press. All right reserved.