The patented Stump Duplex anchor was the first permanent anchor to receive national technical approval in Germany, and the first permanent anchor to be released from the requirement of subsequent monitoring. For over 40 years, this permanent anchor system has been used as a permanent anchor for applications intended to last for more than two years.
The Stump Duplex anchor is a pressure pipe anchor in which the force is transmitted via the back end of the injection body within the pipe. The so-called Duplex pressure pipe works as a force transmission element. The anchor steel tension member is not connected to the grout body. The grout body transfers force from the end of the anchor via compressive force into the subsoil, and so a formation of cracks in the grout body and resulting reductions in the force transmitted between the grout body and the surrounding soil are not to be expected.
Approval (PDF): Duplex Daueranker für Boden und Fels (Z-20.1-6) (An application for extension has been made) (only available in German)