Physical modeling for evaluating the effect of helical anchor configuration and surcharge on wall displacement

Helical anchors with unique characteristics have several applications in constructing and reforming the foundations, as well as soil improvement. However, a limited number of study has been done on the use of helical anchors in walls and slopes stability. In the performed studies, the behavior of the helical anchor’s wall was investigated. For this purpose, a laboratory study was designed to evaluate the wall stability with three types of helical anchors and two types of back-slopes in sandy soil. The aim of the study was to investigate the effect of anchor’s shape and the back slope above the wall on the wall crest displacement. To increase the accuracy of measurements and determine the shear strains, photogrammetry and particle image velocimetry (PIV) methods were employed. Finally, to evaluate its implementation potential, the results were compared with those of the nailing method. The results of modeling revealed that an increase in diameter and the number of the helices led to decreasing in wall crest displacement. The reduction percentages were 30% and 60% respectively for increased diameter and increased number of helices and diameter. If the significant reduction in displacement is required, it is suggested to increase the number of helices without any changes in their diameter. Besides, anchors need a small amount of displacement to be activated and this issue cannot be solved by changing the type of helical anchor. Finally, the results indicated that the slip surface created on the wall of helical anchor using light surcharge is parabolic in shape.