Abstract: Helical piles are widely used in power transmission lines and photovoltaic engineering. It has many advantages, such as convenient construction, large bearing capacity, etc. However, the precision of the existing theoretical calculation method for estimating the uplift bearing capacity of the helical pile is still not satisfying. Based on the cavity expansion method, through the Tresca criterion, a modified approach to estimate the uplift bearing capacity of the helical pile was proposed. Full-scale model tests on the uplift bearing capacity of helical piles were carried out, and the tensile load-displacement response was measured. The uplift bearing capacity of the helical piles tested was obtained with consideration of different failure interpretations. Based on the comparison between the predicted uplift bearing capacity of the helical piles using the method proposed in this paper and the results obtained from the literature, the accuracy and reliability of the theoretical calculation method herein are verified. The results show that the uplift bearing capacity coefficient of the helical anchor increases with the increase of the buried depth of the first helix, and its upper limit value is mainly restricted by the rigidity index of the soil. Compared with traditional calculation methods, the theoretical calculation method in this paper is more accurate, which has about 10% calculation error.

Key words: helical pile, uplift bearing capacity, cavity expansion method, full-scale model test