AGRU America PRO_LiningSystems_2017-1 - Page 10

AGRUFLEX Tunnel Liners Efficient Corrosion Protection for Tunnel Constructions Tunnels are intended to be used for a very long time. For this reason, the sealing system requirements set by authorities are very strict. AGRUFLEX tunnel liners are made of highly flexible VLDPE with thicknesses ranging from 47 mil (1.2 mm) to 165 mil (4.2 mm) and widths between 6 ft. (2 m) and 16 ft. (5 m) and can also be laminated with nonwoven textiles if required. This tunnel liner possesses excellent flexibility, high chemical resistance, and is suitable for drinking water applications. With its light-reflec- ting properties, the white signal layer not only enhances safety in a tunnel, but also offers an easy visual inspection to identify and remedy damage. New Austrian Tunnel Method With the boring approach, the rock is secured with rock bolts, steel arches, or other construction elements after excavation. These are then covered with shotcrete and the tunnel shape is created. The seal carrier, which is a “finely graded” shotcrete, forms the surface for the interior construction work. To protect the liner and for drainage purposes, nonwoven textiles are often installed between the shot- crete and the liner. Cut-and-Cover Approach With the cut-and-cover method, either a HDPE geomembrane or the flexible VLDPE tunnel membrane is used, depending on the project requirements. In most cases, the liner can simply be spread over the tunnel without being attached, but in certain cases, it is fixed to the outer wall of the tunnel. Fastening by means of water stop profiles is a cheap and technically sophisticated option in such cases. The Plastics Experts. 10