Two Diversion Tunnels named as Diversion Tunnel A (L=1.5 KM) & Diversion Tunnel B (L=1.3 KM), as shown in the pictures, are being constructed at 4320 MW #Dasu Hydropower Project by using Drill & Blast method in 4 lifts (layers) of different heights.
Excavation section of the diversion tunnel is adopted a “D” section. The dimensions of excavation section are 24.6m×27.3m at inlets & outlets while 20.4m×24.2m in main underground Tunnels. To avoid flood during flood season and safe construction, gravity concrete dyke in diversion tunnel inlet and outlet was constructed.
The main underground excavation of the tunnel is divided into four layers. The excavation height of the layer I is 8.2m, the height of the layer II is 5m, and the excavation height of the layer III is 8.0m, the height of the layer IV is 3.0m.
Credits: Engr. Tufail