The Ljubno tunnel - Left tube

DARS d.d., Ulica XIV. divizije 4, 3000 Celje, Tel. +3863 544 20 00

INR 55,54 Crore

APPROVAL DESIGN, TENDER DESIGN, FINAL DESIGN, AS BUILT DESIGN, OPERATION AND MAINTENANCE DESIGN

2007

Basic information:
• Total length of tunnel : 260 m
• Area of excavation profile: 141.30 m2
• Maximal overburden height: 25 m
• Minimal overburden height: 15 m
• Longitudinal gradient: constant 1.14 %
The left tube of the Ljubno tunnel is located on the highway section Peracica – Podtabor, which was built in 2007. The Axial distance between the existent right and new left tube is 42 m. The design of the tunnel was performed with the NATM method. The main characteristic of the project is the local soil called »sivica« . Swelling and the inclusion of pyrite, which causes sulphatic corrosion of concrete, are typical for this kind of soil. The thickness of the primary lining is 30 cm. The excavation profile was divided into the top and the bench + the invert. The left tube represents a rarity in the tunnel construction outside the urban settlement since the reinforced secondary lining is of a thickness of 35 cm due to the possible rheological effects of the surrounding rock. The application of reinforced soil in the tunnel portals area adds an architectural value to the tunnel design.