Tunnelling
Tunnelling is a complicated task requiring accurate adoption of technological solutions to prevailing geological conditions. The rock mass properties in the Himalayan region are very complex. There is great need of a professional approach in excavation and rock support methods in such geologically complex rocks.
It may seem simple to dig a hole through a mountain. However difficulty arises when rockfalls, squeezing, water seepage, flowing mass or total collapse occurs which is not unlikely in tunnelling. It is the preparedness in terms of technology, skills and equipment to address these problems, that makes the tunnelling project a success.
Himal Hydro possess a fleet of modern tunnelling equipment including jumbo Boomers for drilling, shotcrete robots, ventilation fans, Alimak raise climbers, mine loaders and trucks. In addition, we have sufficient support equipment like concrete pumps, concrete agitators, cranes, mixers, compressors and generators. Himal Hydro has constructed half of all the tunnels built in Nepal so far. We have qualified and trained crew to undertake any underground works.
Himal Hydro is an Affiliated Member of the International Tunnelling Association (AITES-ITA).
Below, you will get a glimpse of the underground works that we have undertaken including horizontal tunnels, caverns, inclined tunnels and shafts.
Horizontal Tunnels
We have constructed:
- Power Tunnel (34m2), Bypass Tunnel (34m2), Ventilation Tunnel (12m2) and Penstock Tunnel (44m2) of Middle Marsyangdi Hydroelectric Project totalling 750m.
- Headrace (14m2), Tailrace (22m2), Access Tunnel (24m2) and Adit Tunnels (14m2) of Khimti I, totalling 12,000m
- Headrace (17m2), Penstock Tunnel (28m2) and Adits (17m2) of Modi (14MW hydropower plant of NEA) totalling 2,299 m
- Test adit (7.5m2) for Melamchi (planned drinking water supply scheme for Kathmandu) totalling 524m
- Headrace (8.5m2) of Jhimruk hydro project totalling 1,100m.
- Headrace (7.5m2) and Tailrace (8.5m2) of Andhikhola hydro project totalling 2500m
- Test adit (4m2) for Arun III (planned 402MW hydro project of Nepal) totalling 1,400m.
In the course of these projects, we have applied the full range of construction methods from hand operated to advanced mechanised technologies; dealt with very complex geology including tunnelling through the MCT (Main Central Thrust); and achieved the highest tunnelling productivity of 64m/week (at Khimti Access Tunnel).
We have also completed the construction of Penstock tunnel in soft ground using Pipe Canopy Method at Middle Marsyangdi Hydroelectric Project for DDC-JV. Such method has been used in Nepal for the first time.
Inclined and Vertical Shafts
We have constructed:
- Surge Shaft of Middle Marsyangdi Hydroelectric Project: 22m ø, 53m high (biggest underground tank in Nepal)
- Khimti Penstock tunnel: 2.6m ø, 45° inclination, 909m long
- Jhimruk Penstock tunnel 2.1m ø, 45° inclination, 280 m long
- Andhikhola Vertical shaft 4.5m ø, 245m long
- Modi Surge Shaft 10m ø, 40m long
- Modi Penstock Vertical Shaft 4.6m ø, 51m long
- Surge Shafts of Jhimruk, Tatopani, Khimti, Tinau
Himal Hydro is equipped with Alimak Raise Climbers and other specialized equipment for construction of inclined tunnels and vertical shafts.
Caverns
We have constructed:
- Khimti underground Power House
- Andhikhola underground Power House
- Tinau underground Power House
- Tatopani Underground Desilting basin
