Secondo tubo San Gottardo - Lot 241, Main Tunnel North
The present project includes the execution of the second tunnel tube north (2TG), the fault zone drive north, the second stage of the precut, the TBM launch section, the cross connections, the ventilation control centers and the exhibition bays.
Tunnel boring 2TG is carried out with a tunnel boring machine (TBM) with single shield and segment lining up to the north fault zone. Until the arrival of the TBM in the fault zone, the fault zone excavation is carried out from the previously constructed access tunnel by means of machine-assisted full excavation with partial windows. After the TBM has been inspected in the logistics chamber of the fault zone, it is pushed through the excavated fault zone section and drives the second section up to the lot boundary.
Services in detail
In detail, the following main works will be carried out:
Construction 2nd stage Pre-cut 2TG, excavation volume: 24'000m3;
Loose rock section main tunnel excavation area 180m2, length 86 m;
Construction of the underground concrete center, WELK and segment production;
The second tube Gotthard North crosses from north to south first the southern part of the Aar massif (Aare granite, southern gneiss zone) then the Urseren zone (Mesozoic with Jurassic and Triassic, Permo-Carboniferous) and then the Gotthard massif (northern paragneiss zone, Gamsboden granite gneiss). Rocks encountered: Aare granite, gneiss, calcareous schist, clay schist, sericite schist, Zweiglimmer gneiss and granite gneiss.
Construction of the second tube will generate a total of around 7.4 million tonnes of excavated material. 1.8 million tonnes of excavated material will be used immediately to produce new construction material. FEDRO is using around 1.9 million tonnes for terrain modeling and the overburden in Airolo. A further 3.5 million tonnes or so of rock material will be used in the renaturation of the shallow water zone in Lake Uri.