Experimental and numerical investigation of cyclic behavior in single-helix anchors embedded in clay under vertical uplift loading

Abstract

This study investigates the cyclic behavior of single-helix anchors embedded in clay to address the expanding use of helical anchors in transmission tower foundations and submerged pipelines within clay. Laboratory model tests were conducted to assess the effect of the helical anchor configurations on the ultimate uplift capacity, specifically examining the influences from the anchor shaft diameter and helix plate embedment depth. Additionally, this study evaluated the effects of mean load, cyclic load amplitude, and cyclic number on vertical displacement accumulation. Complementing the laboratory experiments, finite element simulations using elastoplastic bounding surface theory were utilized to model the cyclic response of single-helix anchors. Findings from laboratory and numerical simulations indicated that increasing embedment depth and shaft diameter could improve uplift capacity under monotonic loading and reduce displacement accumulation under cyclic loading. A series of cyclic interaction diagrams were generated through finite element simulations for different helical anchor configurations and cyclic loads. By performing regression analysis with the Randional2D function, the cyclic interaction diagrams were transformed from discrete data points into a continuous map, offering a predictive framework for assessing helical anchor stability under cyclic loading and practical insights into the application of helical anchors.