Three-Dimensional Numerical Study of the Tensile Capacity of Helical Multi-Plates Anchors

Nowadays, helical anchors are one of the fastest methods of supporting excavations. The use of helical anchors is increasing, and recently they received more attention in researches. One of the most important factors for the design of helical anchors is their tensile capacity, to which less attention was paid in the literature compared with the helical piles. The present study uses a three-dimensional numerical modeling approach to investigate the tensile capacity of helical multi-plate anchors. For this purpose, first, the adopted numerical modeling methodology is verified. Then, a comprehensive parametric study is performed to investigate the effects of various parameters involving the soil type, soil cohesion, plate diameter, plate spacing, surcharge, and anchor inclination. The present study results show that the tensile capacities of the helical multi-plate anchors increase by increasing the plate’s diameter, surcharge, and soil relative density. However, the soil cohesion and anchor inclination have negligible effects. Moreover, the results indicate that the load-bearing shares of the shaft increase by increasing the surcharge and decreasing the plate diameter. In addition, the results show that the load-bearing shares of the plates stay about constant for S/D≥4 (S and D represent the plate’s Spacing and Diameter, respectively). So that the failure mechanism of multi-plate anchors could be considered as the individual plate for S/D≥4 and cylindrical shear for S/D 4. In other words, the critical S/D ratio is 4. The union of failure zones formed around the plates in displacement contours for S/D 4 confirms this result.