Pull-out behavior of CFRP ground anchors with two-strap ends

Pull-out experiments were performed on three carbon fiber-reinforced polymer (CFRP) ground anchors simulating their applications in different rock types which provided different confinement levels. The CFRP tendons comprised, on the ground side, a prefabricated conical anchor body of high-strength grout in which two CFRP straps were embedded. The anchors reached an average load-bearing capacity of 1384 kN with final failure occurring in the CFRP straps. Grout failure was successfully prevented by an adequate grout selection and installation of CFRP confinement rings to balance spreading forces at the strap ends. The confinement level provided by the surrounding media influenced the activation of the CFRP components in the anchor body by influencing the friction at the CFRP/grout interfaces.