An Overview of Design and Construction practices of Himalayan Hydropower tunnels

• Published in: Journal of physics. Conference series 2020-08, Vol.1608 (1), p.12008
• Main Authors: Karki, Sujan, Chhushyabaga, Bimal, Khadka, Shyam Sundar
• Format: Article
• Language: English
• Subjects: deformation; design methods; field investigation; Hydroelectric power; Hydroelectric power generation; Hydropower tunnel construction; Physics; Rock masses; support failure; Tunnel construction; Underground construction; Underground structures; Weak rock
• ISSN: 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/1608/1/012008

Due to steep terrain and fast flowing rivers in the Himalayan region of Nepal, medium to mega size hydropower projects are constructing day-by-day. Tunnel is one of the best and short routes for water conveyance system for power production. Hundreds of kilometers of tunnels have been constructed and new tunnels are planned in this region. The availability of high head for hydropower generation, the tunnel cross sections are relatively small, up to 6 m diameter in size, and there is high rock cover above the tunnel alignment. This paper focuses on the design and construction practices of hydropower tunnel passes through weak rock mass with high rock cover of the Himalayan region of Nepal. Most of the hydropower tunnels undergo excessive deformation and support failure during the tunnel construction, which delayed the project as well as increases the cost of project. The paper first discusses the available construction practices for tunnel and underground structures. In the second part, the current practice employed during construction in the Himalayas is discussed along with the shortcomings of the methods and how it is addressed in the region.