Strengthening of existing concrete dams using post-tensioned anchors: a state-of-the-art review

Many old dams are in need of strengthening and rehabilitation as a result of aging, deterioration, deficiencies in design and construction, and more stringent safety standards. Post-tensioned anchors are the most practical and cost-effective method of strengthening existing dams subjected to direct tension, sliding, overturning and seismic loading. Post-tensioning technique requires minimum demolition, has only a minor impact on the dam, and is relatively inexpensive using a small number of anchors. About 60 case histories of concrete dams strengthened by post-tensioned anchors were reviewed. The reasons for strengthening were analyzed, and the general design, construction, drilling, grouting, testing, and performance of post-tensioned anchors were outlined. Principal reasons for using post-tensioned anchors were: (1) increasing spillway capacity and dam stability, (2) raising dam height for great storage, (3) upgrading dams to new safety standards, (4) remedying the deficiencies in design, (5) stabilizing concrete cracks, (6) strengthening dam abutments, and (7) reinforcing lock walls or building blocks into coffer dams. 72 refs., 12 figs., 6 tabs