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Nant de Drance Pumped-Storage Power Plant, Switzerland

The fabrication of the subterranean machine cavern as well as the two intake structures require a sophisticated formwork plan as well as expert jobsite support.
Intake structures at the upper reservoir Vieux Emosson are at an altitude of 2,200 m.
PERI and MCE offered a sophisticated formwork plan and support during construction and assembly by a supervisor during the construction work.
Part of the PERI solution is a formwork carriage and wall formwork for the fabrication of the two intake structures with reinforcement concrete slabs with a thickness of up to 3 m.
Dimensionally-accurate prefabricated formwork elements allowed the transition from circular to square-shaped tunnel cross-sections.

Project data

Location: Martigny, Switzerland

The Nant de Drance pumped-storage power plant has an overall capacity of 900 MW. The power plant is located mostly underground at an altitude of 1,700 m above sea level between the two reservoirs of Emosson und Vieux Emosson. The machine cavern for the installation of the pump turbines with its length of 194 m, width of 32 m and height of 52 m is one of the largest subterranean structures in Europe.

  • 17-km long tunnel and gallery system
  • 1.7 million m³ of rubble
  • Construction site at an altitude of 1,700 m above sea level

Requirements

  • 194-m long, 32-m wide and 52-m high machine cavern
  • Intake structures at the upper reservoir Vieux Emosson at an altitude of 2,200 m
  • Varying longitudinal gradients of up to 12 %
  • Transition from a circular to a square-shaped tunnel cross-section
  • Trumpet-shaped widening of the portal
  • Thickness of reinforced concrete slabs up to 3 m

Customer

ARGE GMI (Groupement Marti Implenia), Marti Tunnelbau AG and Implenia Bau AG

Customer's benefit

PERI and MCE offered a sophisticated formwork plan and support during construction and assembly by a supervisor during the construction work.

Portrait of Ulrich Anschütz, Site Manager, ARGE GMI (Groupement Marti Implenia), Marti Tunnelbau AG and Implenia Bau AG
Ulrich Anschütz
Site Manager

My compliments to the Swiss PERI team and to MCE for this extraordinary, customized formwork solution. With up to 300 m³ of concrete per section, we only had a minimum of deformations.

PERI solution

  • PERI Switzerland plans and supplies a modular-type formwork carriage solution in close cooperation with MCE Engineering.
  • To achieve a fast cycle sequence, the tunnel formwork carriage, which is equipped with an electrical drive, can be hydraulically lifted and lowered.
  • The lateral anchoring walers were concreted in advance, also with a hydraulically operable PERI formwork carriage structure.
  • Dimensionally-accurate prefabricated formwork elements allow the transition from a circular to a square-shaped tunnel cross-section.
  • For the extensive construction work above and below ground, also TRIO panel formwork in connection with SB brace frames and climbing brackets were used to be able to form and concrete the walls which are up to 14 m high.