ABSTRACT

Although the history of prestressed rock anchors for dams dates from 1934 and the raising of the Cheurfas Dam in Algeria, current research indicates that the rst U.S. dam to be stabilized by high-capacity prestressed rock anchors was the John Hollis Bankhead Lock and Dam, Alabama. On that project, the rst 6 test anchors and 16 production anchors were installed in 1962. This project was completed for the U.S. Army Corps of Engineers who therefore had sufcient condence in the technology that they were the sponsor for most of the half dozen or so similar applications in the six years that immediately followed. The U.S. Bureau of Reclamation rst used anchors to stabilize appurtenant structures at dams in 1967, while the Montana Power Company was also an early proponent. In those days, the technology was largely driven by the post-tensioning equipment suppliers, employing the same principles and materials such as used in prestressed/post-tensioned structural elements for new buildings and bridges. The “geotechnical” inputs, that is, the drilling and grouting activities, were typically subcontracted to drilling contractors specializing in site investigation and dam grouting in the west, and to “tieback” contractors in the east.