Pullout Stiffness of Elastic Anchors in Slope Stabilization Systems

Abstract

The success of an anchored geosynthetic system depends in large part on the ability of the system to remain tensioned after installation. For pinned‐anchor and spring‐steel collar connectors, the pullout stiffness of the anchor, along with the geosynthetic‐soil system response during unloading, controls the post‐installation fabric tension. Since anchors are typically long, slender driven reinforcing rods, both elastic extension and rigid body translation must be accounted for in determining anchor pullout stiffness. The interface shear strength between soil and anchors mobilizes linearly with relative displacement up to a critical displacement, beyond which it remains constant at the maximum interface shear strength. Solutions for the pullout problem in cohesionless soil are developed, and examples illustrate how pullout stiffness requirements, and therefore anchor lengths, may be determined for spring‐steel collar connectors. A threaded‐anchor‐and‐nut connection, although more difficult to install, is the preferred connector since the loads transferred to the soil are only limited by the maximum pullout resistance of the anchor, not the anchor pullout stiffness.