Tunnel formwork from Peri installed for avalanche protection

Peri's Variokit formwork is being used for concreting nine sections of a 115 m extension of the 300 m avalanche protection system above the B145 road in Austria.

The B145 connects the towns of Bad Aussee and Bad Mitterndorf with the B320 near Trautenfels.

Using the cut and cover method, a 12,8 m wide arched cross-section tunnel has been designed for three lanes of traffic and is concreted above the bottom plate in a single go.

The 600 mm thick concrete tunnel arch extends along a 350 m radius and features a 3,6 to 4,15% lateral as well as 7,5% of longitudinal gradient.

The Peri formwork system enables the side formwork to be hydraulically swivelled inwards when striking, as well as allowing the formwork carriage to be hydraulically lowered.

Peri said in comparison to the conventional, manual striking process, this increases productivity and saves time.

Moving the formwork to the next concreting section is carried out on rails by means of electrical chain hoists. The procedure takes one hour - in spite of the large longitudinal gradient. The external formwork is moved from cycle to cycle with a crane.

Due to the hydraulic support during shuttering and striking, the formwork crew was able to achieve a five-day cycle. Peri said two tunnel sections could sometimes be concreted in the space of one week with the Variokit system.