Connect, no. 111, March/April 2001, p.3
Railway tunnel lining degradation can cause severe disruption to networks and major safety issues for passengers. The problem is caused by falling rock and concrete from existing tunnel linings.
Japan has a particular difficulty because of the number of tunnels with this defect which has caused delays to major rail networks such as the Shinkansen line. To date the solution has been to use a vibrator to bring down all loose materials and carry out local repairs. Repair techniques include concrete injection, wire mesh patching, insertion of steel or wire mesh hoops or the installation of fibre reinforced plastic cladding.
There is available a new approach. This involves using bi-stable reinforced structural composite tubes and injection of adhesive grout using the AdhFAST® fixing system. The composite tube is manufactured in part section (approximately a quarter of the tunnel circumference) and is supplied on a 50-100m roll mounted on a modified railway truck. AdhFAST® fasteners are used to fix the tube to the existing tunnel lining. Adhesive grout is injected and flows down through each set of fasteners. The tube may be applied using three rolls at a time.
The advantages of this system are many. It is fast, needs no secondary support structure and reduces the number of joints over conventional systems. It is a complete cladding system with a smooth surface resulting in easier cleaning and maintenance. It is also very cost effective.
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