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Rockfall protection tunnel “Gandria-Lugano”

Tunnels and structural elements

Project name Rockfall protection tunnel "Gandria-Lugano" Volume 2.500 m³ expanded clay 8-20 mm Location Lugano, Switzerland Year 2000
Designer Owner/Builder Porr Suisse SA


The problems to solve in the design of this artificial tunnel were due: to maneuvering space restricted areas and the need not to interrupt the flow of vehicles and high impact energy of the rocks potentially impacting on the gallery.

Why Expanded Clay:

The choice was to achieve a filling with expanded clay 8-20 blown: in this way it was possible to ensure the ongoing transitability of the road, blowing also allowed economic savings by avoiding more expensive methods of transport of the aggregates traditional (helicopter) and of course the reduction of permanent loads due to the lightness of expanded allowed a sizing easier gallery.


The key determinant for the use of expanded clay has been the ability of maintaining these technical characteristics for the entire life of the work. The expanded clay has no post compaction due to cyclical loads, vibration, loads of snow, wind and rain. It is also not sensitive to cycles of freezing and thawing.

Key Issues:

Blowing, Load reduction, Mechanical protection, and Stability

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