The T5 in T8 tunnels on the second railway track of the Divača-Koper railway

 

Investor: DŽI, Direkcija za Železniško Infrastrukturo 

Phase: PGD, PZR 

Client: SŽ - Projektivno podjetje Ljubljana d. d. 

Issue of proj.doc.: Julij 2010 

Project designer: dr. Vojkan Jovičić, univ. dipl. inž. grad. 

Project leader: dr. Vojkan Jovičić, univ. dipl. inž. grad. 

Project no.: ic 50/10-G/1 

Inv. value: 65.000.000 €

Contract value: 670.000 €

T5 Tunnel

T8 Tunnel

Project description

The existing Divača-Koper railway line runs on topographically very unfavourable terrain and, due to its high inclinations, represents a bottleneck on the Slovenian railway network. Studies have shown that the single-track, electrified Divača-Prešnica-Koper line will no longer be sufficient in the near future due to the increasing traffic from the port of Koper and have substantiated the need to build a second track from Divača to Koper.

The Divača-Koper railway track is part of the Pan-European Corridor V, which is fully included among the priority transport projects of the EU. In April 2005, the Government of the Republic of Slovenia adopted the Regulation on the National Location Plan (hereinafter: NLP) for the second track of the railway line on the Divača-Koper section.

The route of the new line is designed to allow the connection of the Trieste-Divaca railway line. The project foresees the preparation of an amendment to the NLP for the second railway track Divača-Koper into a DPN for the new double-track Divača-Koper line, the preparation of investment documentation for the new double-track Divača-Koper line, the purchase of land on the basis of the NLP Regulation for the second track of the railway line on the Divača-Koper section, and the construction of the new railway line from Divača to Koper.

The T5 and T8 tunnels are planned as part of the single-track railway link Divača-Koper on the Črni Kal-Koper section.

Tehnical features

The T5 tunnel is a single-track, single-tube railway tunnel to be built over a length of 136 m. On the southern side of the tunnel, a box structure of 21 m will be constructed as the portal structure of the T5 tunnel, which, due to the configuration of the terrain, will also partly act as a gallery. The tunnel will be excavated along its entire length in layers of flysch, namely alternating layers of marl, mudstone and sandstone. The tunnel is located in the Zanigrad thrust zone, which is a zone of several horizontal, parallel thrusts. These tectonic structures generally result in tectonically damaged and more severely fractured rock in this zone.

The T8 tunnel is a single-track railway tunnel with a parallel service pipe, which will be built in a length of 3808 m. On the northern side of the tunnel, a 14 m long cut and cover is foreseen as the portal structure of the T8 tunnel. Between the temporary and the final southern portal, a cut and cover and a classical portal structure of 30 m length is planned. The entire route of the T8 tunnel lies on terrain that is made of Eocene flysch. The surface is covered by a 1,5 m to 9 m thick layer of soil, consisting of deluvial clays and gravel, while below it there is a layer of weathered flysch rocks several metres thick. Due to the intense tectonics, the dip of the layers often changes even over short distances.

Participating designers and project organisations

  • SŽ-PP d.o.o. - lead partner

  • Lineal d.o.o. - access roads and preparatory works

  • Ponting d.o.o. - viaducts

  • Elea iC d.o.o. - tunnels

 
Construction, Underground structuresPetra Bukovinski