Shotcrete is frequently used in the building of key elements within a hydroelectric plant, stabilizing and adding support to structures such as headway and tailrace tunnels, and caverns.
Pneumatically applied concrete is a rapidly executed support method, and as such, it is often used in the building and securing of embankments and canals; as well as a means to secure underground work such as pipelines in hydroelectric power plants.
How does a hydroelectric plant work?
Put simply, a hydroelectric plant exploits a drop in elevation in any given terrain to store large amounts of water: when released, the falling waterhead generates kinetic energy that is captured and transformed into electrical energy by turbines. The water is subsequently returned to the river and may be re-used downstream for human consumption or in another hydro project.
Stringent environmental regulation in Europe means that headrace tunnels, caverns and tailrace tunnels in most hydroelectric plants are all dug underground.
Norway is a leading proponent in the sector, with over 95% of its power production stemming from hydroelectric plants. The Nordic country hosts more than a third of the world’s 600 underground hydroelectric plants.
Shotcrete and underground elements of the hydroelectric plant
A hydroelectric plant involves the construction of many underground structures, including headrace or supply tunnels, tailrace tunnels and caverns through which water circulates at high pressure after the jump.
A combination of shotcrete and bolts are used to support and secure the tunnels through which run the pipes channeling the waterhead.
In countries like Norway, where the rock mass is generally of good quality, water conveyance tunnels can be built without the need for additional support; although visible cracks and the crown of the tunnel should be sealed with shotcrete to ensure its structural integrity.
The parts of a plant most exposed to pressure from the waterhead include the penstock, the pipe within which the sudden loss of height occurs, as well as the distributor tunnels that feed the turbines. These sections are subjected to enormous stress and require additional coatings with a high-performance shotcrete to protect them against wear.
Mechanized concrete spraying equipment can also be used as a scaling machine, using high pressure water to dislodge loose rock and prevent accidents.
If you want to find out more about some of the equipment that can be used to spray shotcrete in hydroelectric projects, you can find more information here.
- Simon Reny, “Péribonka Hydroelectric Development Project: Contractor Converts Preblended Dry Components to Wet Shotcrete”, in Shotcrete Fall 2008, Last accessed 21/06/16
- U. Deere & G. Lombardi, “Lining of pressure tunnels and hydrofracturing potential”, Lombardi SA, Last accessed 24/06/16
- Einar Broch, “Tunnels and Underground Works for Hydropower Projects”, Muir Wood Lecture April 2010, International Tunnelling and Underground Space Association (ITA), Last accessed 21/06/16
- Prof Atil Bulu, “Hydroelectric Power Plants”, Hydraulics Division, Civil Engineering Department, Istanbul Technical University, Last accessed 24/06/16
- “Energy & Water Resources in Norway: Facts 2015”, Norwegian Ministry of Petroleum & Energy, December 2014, Last accessesd 21/06/16