Analytical Model of In-Situ Root-Inspired Ground Anchor Actuation and Pullout-Article

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The paper presents an analytical and reliability-based framework for designing root-inspired ground anchors (RIGAs), which deploy root-like linkages inside a drilled hole to improve pullout resistance. During installation, hydraulic force brings the mechanism’s collars together, causing its linkages to penetrate surrounding soil; cured grout then locks the mechanism in its expanded shape.<br /><br />The model estimates actuation forces by analyzing each linkage assembly as a hinged frame at successive stages of deployment. Soil resistance is represented by a pressuremeter-inspired stress–displacement model, while interface friction is modeled separately for drained and undrained conditions. Peak actuation stresses are expected at roughly 10–20 degrees of linkage deflection, after which reduced contact with unpenetrated soil tends to lower resistance. Pullout capacity is estimated using established analytical methods for plate anchors, adjusted by an assumed factor of 60% to represent RIGA geometry.<br /><br />The authors implemented the approach in Monte Carlo simulation software, allowing variability and uncertainty in soil properties to inform predicted performance and reliability. An example based on data from the Spring Villa geotechnical test site in Alabama produces actuation-force trends consistent with prior field observations.<br /><br />The framework offers a way to estimate mechanism demands and anchor capacity before extensive full-scale testing is available. However, its predictions depend on assumptions including quasi-static actuation, approximately isotropic limiting soil stresses, negligible linkage-pin friction, and the 60% pullout-capacity modifier. The authors also note uncertainty in soil-interface behavior and the need for further field data and finite-element studies. Despite these limitations, RIGAs may enable shorter anchors, faster installation, and lower material use and emissions than conventional grouted anchors.

Keywords

root-inspired ground anchors

RIGA

pullout resistance

hydraulic actuation

linkage deployment

grouted anchors

pressuremeter model

Monte Carlo simulation

soil-structure interaction

reliability-based design