Tunnel construction
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Tunnel construction

Tunnel construction Modern traffic tunnels are increasingly planned for a A long-term, trouble-free tunnel operation with low functional service life of more than 100 years. For this operating and maintenance costs can be achieved with reason they must be protected extensively against the a professionally installed sealing system. In addition, a effects of groundwater and water penetrating through rock fissures. The construction and sealing specifications are correspondingly strict, especially with respect to the required service life. The level of hydrostatic pressure and the agressiveness...

Geosynthetic functions Sealing Basically, sealing systems have two functions in the construction of modern traffic tunnels. They divert the mountain water away from the tunnel and they protect the supporting structure from the potentially aggressive particles in the water. This sealing and protection function must remain intact over the service life of the tunnel. To achieve this, geomembranes, particularly those manufactured from flexible polyolefins, are being used in thicknesses up to 4 mm. The type of sealing system selected will depend on factors such as geology, hydrology and stress...

Sealing materials and their production To refurbish a tunnel seal requires a great deal of technical effort and massive financial investment. To prevent this occurring, it is sensible to select products and sealing systems that will ensure long-term effective- For this reason, Carbofol® tunnel geomembrane by NAUE meet the following criteria: Carbofol® geomembranes for tunnel construction Geosynthetic materials manufactured from polyethyl- → good mechanical behaviour with high flexibility ene (PE), which is highly resistant to chemicals and ecologically safe to the environment, meet highest...

Production All raw materials for the production of geosynthetics each product having its own specific plan. The results used in tunnel construction are subject to an intense of the quality controls are documented in a final in- and strict incoming quality assurance. The specifica- spection certificate according to EN ISO 10204. tions agreed with the suppliers are checked at the plant and only after release by quality assurance will These quality control measures which are performed for the raw material be accepted for production. all products meet the respective requirements of the current...

Carbofol® sealing systems In principle, there are distinctions made in tunnel construction between a sealing against water pressure and against seepage water. For seeping water, a Carbofol® tunnel geomembrane that is 2 mm thick can be used as an umbrella seal. For occuring hydrostatic water the use of an all-around sealing (360°) with a separation system is the required solution. This results in the following sealing systems: 1. Seepage water sealing sytem (SWA) “Drained tunnel“ The structure is protected against water by a Carbofol® tunnel geomembrane with an umbrella sealing system (Fig....

Carbofol® seepage water sealing system (SWA) Drained tunnel The Carbofol® sealing system is carried out with a to discharge it away from the tunnel structure. Drained 2 mm thick Carbofol® tunnel geomembrane according tunnel structures are constructed using either cut and to the cross-section in fig. 12 (from the inside out): cover or mined technique. Water built-up is not expect- ed to occur when the drainage system has been → Carbofol® tunnel geomembrane 2 mm with planned and constructed carefully. signal layer → Secutex® R 551-B2 (≥ 500 g/m² or ≥ 900 The criteria listed below are required...

Carbofol® hydrostatic water pressure with segmental waterstops (DWA) Water column Block joints The main component of the sealing system comprises of The circumferential segmental block waterstops a 3 mm thick Carbofol® tunnel geomembrane, which is between segments have, essentially, the follow- installed as a single circumferential layer to resist hydrostatic water pressure. An effective visual, quality a) Restricting the flow of seepage in the event assurance of the entire sheet is created by a lightreflecting signal layer on the Carbofol® tunnel geomembrane side that is faced to the...

Carbofol® sealing system against hydrostatic water pressure with integrated injection system (DWA-I) For the Carbofol® DWA-I system, the basic design is identical to that of the DWA system (page 8). Injection tube and connection Additionally, an injection system is integrated, which permits retroactive sealing. Carbofol® tunnel membrane Secutex® protection geotextile Shotcrete The integrated injection connections Fig. 18: Injection connection with tube on Carbofol® tunnel geomembrane → potential damage caused by subsequent construction (e.g., installation of steel reinforcement) → exposed...

Carbofol® system and drainage system – cut and cover construction, including portal sealing In contrast to the mining technique of a tunnel, the Backfill work can cause unintended damage to the cut-and-cover method takes place in the open. The Carbofol® tunnel geomembrane. For this reason, a Carbofol® tunnel geomembrane is placed loosely on the 3 mm thick protection Carbofol® tunnel geomembrane protection Secutex® geotextile, which is installed first will provide excellent protection against the high onto the sealing carrier layer (construction concrete) stresses during backfill operations....

Requirements for the sealing carrier system The shotcrete formation layer, which simultaneously serves as the backing and the fixing support for the sealing system, is an important criterion for the Rounding radius (ra) functioning of the sealing geomembrane in mining technique tunnel construction. The sealing carrier system is to be constructed such that a full-plane interface connection of protection layer and geomembrane is ensured without the geomembrane being Support arch overstressed or being folded. The 5 to 15 cm thick shotcrete shell, which can be far thicker, depending on the...