In-situ Test Study on Vertical Uplift Bearing Capacity of Screw Pile

In this paper, the vertical pull-out bearing capacity of the screw cast-in-place pile is studied. In-situ static load and internal force test are carried out on the screw cast-in-place pile and straight rod pile respectively. The axial force distribution of the pile under different loads is recorded, and the difference of vertical pull-out bearing capacity between the screw cast-in-place pile and straight rod pile and the reasons are compared and analyzed. The results show that the vertical uplift capacity of screw cast-in-place pile can be increased by 5%-15% compared with that of straight rod pile. With the increase of uplift load, the lateral resistance advantage of screw pile thread section begins to play, and the axial force of pile decreases faster in the thread section, and the axial force curve presents a broken line. Under the same uplift load, the displacement of the screw pile is smaller, and the uplift force is mainly generated by the screw segment, and the lateral friction of the upper straight rod segment is not as good as that of the straight rod pile.