Effect of Cutoff Wall in Seepage Analysis of Dadin Kowa Dam in Gombe State

摘要

Dams are essential elements in any modern society and have great economic values. However,they present potential catastrophic risk of failure which is mostly attributed to seepage. To control seepage,effect of dam cut-off wall at mid sections of the dam having STA 455 was analysed using the Geo-slope SEEP/W2D finite element method software. The Dam consist of an upstream blanket, 25m deep slurry cut-off wall,which projects into the core and bedrock in the river sand; a grout curtain in under the cut-off wall in thefoundation cement and chemical grouting of the river bed and bedrock and a relief well and horizontal draindownstream. Results showed that the annual seepage value at 37m maximum water level of STA 455 was31.2585 m3/year with the cutoff wall while 511.4825 m3/year was recorded without the cutoff wall, the seepagevalue is far too high compared to the value with the cutoff wall in place. To ensure dam safety and villages atdownstream area, it is recommended to use cut-off wall which helps in reducing seepage values. Routineinspections must be carried out by assigned personnel to check against dam break.