The “three-component approach” for high waterproofing requirements is a new waterproofing system especially for high water pressures. It is presented here as a possibility that can be implemented in construction practice. A geosynthetic clay liner (GTD – or bentonite mat) is installed as the first layer behind the 3 mm thick tunnel sealing membrane that retains water under pressure, instead of the usual protective and drainage geotextile. Laboratory tests as well as practical application on the tunnel construction site show that the use of bentonite mats and plastic sheet membrans (PSM) as a double-layer pressurized waterproofing with simultaneous extended ridge gap injection (block backfill) is a promising alternative to the double-layer system with PSM and could represent a new state of the art.
In the course of a large-scale infrastructure programme of the Egyptian government, including the creation of a special economic zone in the Sinai Peninsula, Egyptian construction companies were commissioned to build several tunnels; the construction times of these projects were quite ambitious.
Germany’s national railway company “Deutsche Bahn” plans for new railway lines with a number of long tunnels in jointed rock. In view of their length, these are suitable for TBM heading. In the past, TBM heading in jointed rock have often been connected with difficulties, which have led to exceeding of the planned construction times and costs.
At the closing ceremony, the participants agreed: It was an excellent World Tunnel Congress 2023 in Athens. In numbers this means: More than 420 presentations from over 45 countries in the lecture sessions and an extensive exhibition of the tunnelling industry.
