Field Experimental Study on the Uplift and Lateral Capacity of Deep Helical Anchors and Grouped Helical Anchors in Clays

This research aims to investigate the bearing capability of deep helical anchors and grouped helical anchors under uplift or lateral loads using field experiments. Grouped helical anchors may serve as a viable alternative to traditional deep foundations, offering increased resistance against uplift and lateral forces. The study of group effect primarily focuses on vertically installed helical anchors, with few data available on various configurations of grouped helical anchors. This research includes a total of 12 single-helix anchors, 4 double-helix anchors, and 4 grouped helical anchors, with anchor plate diameters of 400 mm and maximum embedment depths of 7.4 m. There are two configurations of grouped helical anchors, each with different platforms. This article studies the effect of some factors, including the embedment depth, the number of anchor plates, the spacing between anchor shafts, the selection of failure criteria, and the group effect. The primary findings indicate that adding the anchor plates to single-helix anchors without extending the shaft length does not increase uplift or lateral capacity. In this soil condition, the group efficiency of double-helix anchors is higher than 1. By comparing the group efficiency and economy of the G1 and G2 grouped helical anchors, it is highly recommended to use the G2 configuration. The data obtained from this work may also serve as a valuable tool for validating numerical models used to analyze interactions among grouped helical anchors.