Introducing expandable mechanical plate anchors for onshore and offshore anchoring

Abstract

Soil anchors are among the most widely used reinforcements to stabilize unstable soil mass or stabilize and anchor structures built in onshore and offshore regions. Anchors are generally installed in soil and rocky environments by penetration and embedment methods. These methods are classified into two main groups of grouted and mechanical anchors. In the present study, Expandable Mechanical Plate Anchors (EMPLAs), a new generation of mechanical anchors, are introduced and their bearing capacities are evaluated. EMPLAs can be implemented, locked, and activated in the soil more cheaply and with a lower driving force. Previous studies have validated the efficiency of these anchorages based on the experimental test results. Here, it is tried to evaluate the effect of properties of anchor plates such as their shape and curvature on the locking mechanism, as well as the ultimate bearing capacity of reinforcement and drop rate of locking force under a constant pullout speed rate. Furthermore, the ultimate bearing capacity of the anchors is calculated using two methods of 1) the well-known theories for calculating the tensile bearing capacity of plate anchors in cohesionless soil and 2) numerical modeling using finite element software. The results from both methods showed that the plate curvature intensity had a great impact on the plates opening rate and, consequently, faster locking and activation of the reinforcement at the higher embedment depth. Eventually, the effective zone of the soil at the top of the expandable plates during a 90° rotation of the plates and lockage of the reinforcement was monitored using the Particle Image Velocimetry (PIV) technique.