ABSTRACT
The Forces Motrices Hongrin-Léman hydroelectric scheme is a pumped-storage plant in operation between Lake Geneva and Hongrin Reservoir, in Western Switzerland. In addition to the natural catchment area, the upper reservoir is supplied with water drained from 8 different intakes through a large supply network of tunnels. In the eastern part, there is a 8 km long tunnel with a specific 1 km stretch of tunnel showing significant damages which occurred only few years after commissioning. The tunnel cover is about 200 m and the gallery has a 2.5 m internal diameter. A combination of factors leads to this damaged structures, convergence and stability issues. The rehabilitation concept is designed as a new concrete circular lining, with a construction methodology developed together with the Contractor to tackle all tricky logistical issues due to a very narrow underground space and remote access conditions.
