|PRODUCT||izolNETEX 3.100||34 000 m2|
|LOCATION||Prague, Czech Republic|
|INSTALLATION||2009 – 2010|
The Blanka complex of tunnels in Prague is currently the largest underground construction project in the Czech Republic. It is being built within the development of the north-western part of the inner city orbital road. The extension of the works is extraordinary, the total length of this section is 6,4 km. After its completion it will join up with the already existing 17 km of the city circle. The whole project consists of several successive tunnel sections, bothmined and „cut and covered“.
The „cut-and-cover“ tunnels are constructed by 2 methods. Firstly the „bottomup method“ where a trench is excavated and the tunnel is constructed within, starting from the bottom slab followed by the walls and the roof.
Limitations of urban area conditions where early reinstatement of roadways andsurface services is required result in the use of the „top-down“ constructionmethod.
Within this method, side support walls are constructed from ground level using slurry walling. When completed, the tunnel roof follows. After a relatively short time period the surface can be reinstated except for access openings. Excavation machinery then carries out the main excavation under the permanent tunnel roof. The base slab constructing follows.
To make the excavation easier and to achieve a smooth clean fair-face concrete from the lower side of the roof slab, izolNETEX 3.100 is used. The product is a special one-side smooth geotextile which is applied on the lean concrete just before reinforcing and concreting of the roof slab.