Abstract:
Karora Hydropower (11.8MW) project site is located in Kuz Kana / Karora area
on the Khan Khwar River about 25 km from Besham and 30 km from Alpuri Town – which
is the district headquarter of Shangla District – Swat. The Project is accessible through
Besham – Mingora road. The 2960m long Headrace tunnel is designed as a Horse shoe
shape of diameter 2.6m concrete lined. The tunnel is constructed by Ghulam Rasool and
Company (GRC) under the supervision of Pakistan Engineering Services (PES) as a
consultant. Conventional methods like drilling and blasting were used for the excavation
of headrace tunnel. This study is focused upon evaluating rock mass classifications such as
RMR, RQD and Q system. This tunnel is situated in the geological settings of Karora
Group which comprises of meta-sediments.The field surveys were conducted to analyze
the lithology, shows the lithology is complex, contain highly sheared zones, wedges and
quartz veins that were encountered during the excavation of Tunnel.
During the study RMR and Q system results show the rock categorization along the
tunnel route from “Good to Very Poor” Quality. The support system designed for headrace
tunnel consists of Rock bolts, Shotcrete, Lattice girders and Wire meshes.
