Numerical Analysis for the Evaluation of Pull-Out Capacity of Helical Anchors in Sand

Plate anchors play a significant role in the stabilization of various geotechnical structures. In recent years, the use of helical anchors has extended beyond their traditional use in the foundations. Faster installation and instant loading capabilities have increased their use in multiple infrastructure applications. Through the past few decades, researches have been carried out many studies to determine the pull-out capacity of plate anchor, which has led to the development of many analytical solutions. Unfortunately, the current understanding of helical anchors is unsatisfactory to lay the appropriate framework to be followed by practicing engineers. To have an economic and safer design which leads to increased confidence in design, this study is aimed to use numerical modeling techniques to understand the behavior of helical anchors in the sand and their failure mechanism. Subsequently, the present study focuses on the numerical investigation of pullout capacity of helical anchors with the consideration of various important parameters like embedment depth (H) and anchor plate diameter, D provisioned in the sands of the wide range of relative density i.e. loose, medium and dense sand. It is noted from the results of the present study that the pullout capacity of an anchor provided at sufficiently high value of embedment ratio (H/D) is in excellent agreement with the exact solution proposed by previous researchers. Moreover, a numerical analysis using finite element method with consideration of upper and lower bound limit analysis is carried out for the evaluation of the pull-out capacity of plate anchor (q(u)) in multi-layered sand deposit and the variation of qu with H/D ratio is also presented. Furthermore, the associated failure mechanism of the plate anchors is also analyzed and discussed thoroughly in the present work.