Abstract
Abstract Water seepage is one of the most important features of embankment dams. To prevent and reduce seepage, it is necessary to seal the dam. Plastic concrete cutoff walls are one of the most efficient methods in waterproofing the foundation of embankment dams on permeable alluvial substrates. Sufficient resistance to loads, low permeability to maintain dam sealing, high ductility compatible with the foundation and deformation under load without cracking are the main requirements in plastic concrete cutoff walls. In this paper, the construction and implementation of the cutoff wall of Karkheh Dam, which is one the world’s largest water sealing projects, was studied. In addition, a numerical model using Seep-3D software was developed to evaluate the efficiency of the cut-off wall to decrease the seepage over the dam’s foundation. The numerical results validated by instrumentation statistics resulted from 17-years dam operation. According to the results, after the drainage of the reservoir, the cutoff wall optimally reduced the hydraulic gradient by 0.08 from 2.35 and the water leakage by 3.1 m/s from 18.3 m/s.
Highlights
Karkheh Dam located in Khuzestan province in Iran and 25 km northwest of the city of Andimeshk became operational in 2001 to control the floods of Karkheh RiverThis work is licensed under the Creative Commons and extensive financial studies, implementation of a cutoff wall was considered as another option for sealing of the dam foundation
The results of this study indicated that the cut-off wall helped to decrease both total seepage and the hydraulic gradient; for instance, total seepage was cut to 25% and the hydraulic gradient was reduced from 0.2 to 0.095
The rate of water flow and the distribution of water potentials in a one-dimensional soil column under steadystate conditions can be obtained by solving the Darcy or Buckingham-Darcy equation
Summary
Karkheh Dam located in Khuzestan province in Iran and 25 km northwest of the city of Andimeshk became operational in 2001 to control the floods of Karkheh River. This work is licensed under the Creative Commons and extensive financial studies, implementation of a cutoff wall was considered as another option for sealing of the dam foundation. The reason for the selection of this approach was the slow implementation of the project using the “curtain injection” method, in addition to the economic and technical problems. Karkheh’s conglomerate foundation consists of water-resistant horizontal mudstone layers each having a thickness of 3 to 9 m. The permeability of these layers, which are bedded almost horizontally, is in the range of 10−7–10−10 m/s. Geotechnical investigations revealed that these layers are continuous enough to provide different strata for each conglomerate layer confined by the mudstone layers.
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