Drainage of the underground structures of the Nurek hydroelectric station

Abstract

1. In connection with the considerable depth of the underground structures of the Nurek station below the groundwater level, a necessary condition for their rational design and construction is the use of drainage to lower the groundwater level to acceptable values. 2. For the given hydrogeologic conditions, layout, and designs the construction of general drainage in the region of the penstocks (right bank) and local drainage in the spillway and other free-flowing structures is the optimal decision for the creation of drainage of the underground structures. 3. The main type of local drainage for underground free-flowing structures under the construction conditions at the Nurek station is hole drainage, which is distinguished by a high draining capacity, simplicity of installation and restoration, possibility of combining it with grouting operations, and economy. 4. Drainage bands of granular materials, precast members, etc., and pipes for discharging the drainage waters should be positioned in tunnels in rock within the limits of the lining in order to avoid overbreakages and complication of traffic movement. 5. To establish the effectiveness of drainage in underground structures, it is necessary to provide for the installation of appropriate monitoring and measuring devices for determining the level of groundwaters and their presure on the lining and the quantity and quality of the water being drained.