Experience with subsequently installed drainage systems inside of masonry dams

摘要

At the beginning of the 20th century many masonry dams with build-in drainage systems were constructed in Germany. Several circumstances caused the malfunction of these systems after more than 60 to 90 years in operation. In 1965 The Ruhr-River-Association started the rehabilitation of these dams by blasting a drainage gallery into the dam of the Lister Reservoir. From 1997 to 1998 the Ennepe Dam was reconstructed by mining the drainage gallery with a tunnel boring machine (TBM). The rehabilitation concept was based upon a detailed feasibility study, applying different numerical simulation methods. The official permission required the proof of the performance of the structure by several measurements. The comparison of the real measurings with the assumptions from the "a-priori"-simulations proves the successful rehabilitation and is a valuable tool for reservoir monitoring in the next years of operation.