Installation procedures of TENAX geocomposites for tunnels, Tenax geosynthetics

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Installation procedures of TENAX MDP geocomposites for tunnels

TENAX MDP geocomposite can be used either on PVC geomembrane liner tunnel and on GCL liner tunnel. Care shall be taken to keep the geocomposite clean and free from debris prior to installation. The excavated surface of the rock tunnel should be as smooth as possible. If necessary, a thin layer of shotcrete can be used. TENAX MDP 1200 has an edge where the membrane is not cuspated; this edge is used to give a continuity of the protection layer at the contact between two adjacent rolls.
Adjacent rolls shall be but jointed and the geotextile and geomembrane lateral edges shall be overlapped 100 mm. If required, joint between adjacent geocomposite rolls can be waterproofed through the use of a butyl rubber tape with the adhesive from both sides. In some cases (when it is not necessary to guarantee a filter to the draining system) it is possible to use a membrane MC 1200 or a cuspated geonet NDP 1250 instead of MDP 1200.
The geocomposite must be applied with the geotextile in direct contact to the rock; the TENAX MDP 1200 must be fixed to the rock through gun nails or anchors, with the head diameter greater than 40-60 mm. The length of the nail must be chosen accordingly to the rock characteristics. The number of anchor nails should then be chosen in order to withstand the weight of the geocomposite (especially at the top of the tunnel) and of the primary lining system that will be fixed over it. There are two primary lining system: PVC geomembrane liner and GCL panel liner.

PVC GEOMEMBRANe liner
PVC GEOMEMBRANe liner

GCL panel liner

GCL panel liner

The connection between the PVC geomembrane primary liner and the geocomposite is made by seaming the PVC membrane with small welding spots on a PVC strip fixed under the head of the anchor nails.

The connection between the GCL panel and the geocomposite is made by fixing the GCL panels with a screw anchor with a HDPE disk.

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TENAX MDP

TENAX International B.V. • Geosynthetics Division
Via Ferruccio Pelli, 14 CH-6900 Lugano, Switzerland • Tel +41+91.9242485 • Fax +41+91.9242489

geo@tenax.net

TENAX SpA - Geosynthetics Technical Office (GTO)
Viale Monza, 1- 20125 Milano (MI), Italy • Tel. +39 02.26113532 • Fax +39 02.28971107

gto@tenax.net

TENAX SpA • Divisione Geosintetici
Via dell'Industria, 3 • I-23897 Viganò (LC), Italia • Tel +39 039.9219307 • Fax +39 039.9219200

geo@tenax.net