INVESTIGATION AND REMEDIATION OF THE CAVERN IN THE VRATA TUNNEL ON THE ZAGREB – RIJEKA
Mladen GARAŠIĆ, Meho Saša KOVAČEVIĆ & Danijela JURIĆ-KAĆUNIĆ - (39/1,2010)
In the Dinaric karst system in Croatia some 11500 speleological
objects have been explored so far, more than 1000 of which
were discovered during construction works. Such speleological
objects without natural entrance on the terrain surface (which
are called „caverns“) have been discovered on the construction
sites of the highways. Over the past twenty years they have
been systematically investigated and treated. A special kind
of remediation was conducted in the cavern’s large hall of the
„Vrata“ tunnel on the Zagreb – Rijeka highway. Due to size,
shape, cavern’s position and hydrogeological parameters within
the karst system it was necessary to design and construct a 58
m bridge over the cavern. In addition, the cavern’s vault had to
be reinforced and stabilized, as the overburden was very thin.
The beam-and –stringer grid with special anchors was used.
The cavern’s rehabilitation in the „Vrata“ tunnel was a unique
undertaking, and the bridge (without piers) is the cavern’s longest
bridge in the world.