EGMA - Applications: Tunnel - The synthetic liners can be used in all type of tunnelling works

Owing to the inherent complexity of construction, tunnels must have a life expectancy of several decades.

All components of these works should have similar characteristics, especially the waterproofing system. The waterproof liner protects and makes the construction safer. Over its whole working life, it allows considerable cost savings in terms of maintenance and repair. Since the creation of the first tunnels, water seepage has been one of the main problems. Virtually no tunnel is ever bored into a completely dry substrate.

Historically, water has been one of the most serious problems encountered in underground works
and it requires extremely expensive repair and renovation works.

The essential characteristics of a waterproofing liner for tunnel works are a high physical-chemical performance with minimum maintenance during its lifespan.

This means optimisation of results from every perspective: mechanical resistance, resistance to ageing, flexibility, ease of installation and – last but not least – environmental protection.

The main characteristics of liners for tunnel works are:

	Excellent weldability
	Softness and flexibility
	High ultimate elongation (dimensional variation of the membrane when subjected to mechanical stress)
	Tensile strength (the membrane can resist tensile stress without tearing)
	Durability
	Adaptability to irregular substrates
	Maintains its integrity even in the case of structural movements or soil subsidence
	High electrical resistance
	Suitable for installation in humid places
	Resistance to static puncturing
	Resistance to dynamic puncturing
	Chemical resistance
	Resistance to bacteria and fungi
	Resistance to micro-organisms
	Resistance to roots
	Fire resistance
	Compatibility with drinking water
	Signal layer surface (essential feature to check the liner once installed. Any surface damage of the liner is immediately shown by the different colour appearing from the surface underneath)

Another basic aspect is ease of application, where the sealing of the waterproofing membrane should allow for the execution of complex details and particulars, especially in difficult situations on site.

This is essential for the successful result of the overall system.

The following characteristics should be considered:

	Easy weldabiltity and workability of the material
	Compatibility with special accessories
	Ease of performing quality tests in the post-application stage (specifically, checking the welded seams)

Selecting the correct waterproofing membrane with the required mechanical characteristics is essential to the success and durability of the project.

The membrane must be able to adapt to the extreme conditions that may be encountered in this type of project.

All synthetic liners for tunnel works (PVC or TPO) are formulated and manufactured to meet these specific requirements.

They can be selected according to their mechanical and performance characteristics, as regards: ultimate elongation, tensile strength, resistance to static and dynamic puncturing, chemical and biological resistance, fire resistance, compatibility with drinking water.

The synthetic liners can be used in all type of tunnelling works:

	NATURAL TUNNELS (with or without water under pressure)
	MAN-MADE TUNNELS
	CUT AND COVER TUNNEL