Tunnels are either drained or undrained. The design of drained tunnels manages the relief of hydrostatic pressure on the waterproofing layer and transports the water away in the tunnel invert.

ABG Geosynthetics have developed a range of geocomposite drainage products specifically for tunnel drainage.

The Cavidrain® range is a pre-formed cavity drainage system specifically designed to relieve the effects of water penetration from tunnels and is suitable for both remediation and new build. Cavidrain® can be used in both tunnel walls and tunnel invert drainage.

Cavidrain® has been specifically developed to provide a highly effective drainage system and mitigate the adverse effects of water on tunnel structures.

Tunnel Drainage Specification, Part of ABG Tunnelling CPD

Extract from ABG's Tunnel Drainage CPD. Click to register for the CPD.

Tunnel Invert Drainage

Cavidrain® Invert provides a pre-formed drainage layer into which the concrete floor slab can be easily cast. Cavidrain® Invert at just 20, 40 or 60mm thick replaces the crushed stone and pipes traditionally used to collect and transport away infiltration water.

Cavidrain® Invert is optimised for high in-plane flow velocity to mitigate problems caused by mineral calcification. Cavidrain® Invert has been designed to achieve a maximum bearing area and withstand normal installation loadings. The final compressive load is taken by the concrete infill.

Cavidrain® Invert has been used successfully throughout the world in several prestigious tunnel projects.

Benefits:

  • Simplified invert drainage system
  • Reduced excavation requirements
  • Significantly reduced project time scales
  • Materials & labour cost reduction
  • Reduced installation requirements compared to traditional invert drainage methods
  • Improved drainage capacity
  • Minimised damage caused by mineral calcification
  • Designed in bespoke panels to suit tunnel dimensions

ABG Cavidrain Invert Drainage geocomposite for tunnel drainage

Tunnel Wall Protection & Drainage

Cavidrain® Protector provides a free draining layer to collect infiltration water from behind tunnel linings as well as providing protection from physical damage. Cavidrain® Protector acts to minimise the build-up of hydrostatic pressure, thus protecting and enhancing the effectiveness of the waterproofing layer.

Tunnel construction using ABG Cavidrain® drainage geocomposite

See our article on innovative tunnel drainage being applied 

Cavidrain® Protector provides significantly more drainage capacity than a traditional geotextile fleece.

Benefits:

  • Enhanced integrity of the tunnel lining system
  • Improved drainage capacity, especially under high compressive loads
  • Minimised damage caused by mineral calcification
  • Installed in the same way as the geotextile
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Tunnel Wall Combined Drainage & Waterproofing Liner

Cavidrain® Liner is a combined drainage and waterproofing liner that is welded or taped to form an integral waterproof system. Cavidrain® Liner cuspated LLDPE sheets are easily fixed to the smoothed excavated walls with a sealed fixing detail and the system is finished with sprayed concrete. The rebound loss is significantly lower than applying a SCL onto a smooth PVC liner.

Benefits:

  • Simplified tunnel lining system
  • Materials & labour cost reduction
  • Reduced installation requirements
  • Improved drainage capacity
  • Minimised damage caused by mineral calcification
  • Reduced rebound loss of sprayed concrete
ABG Cavidrain Liner geocomposite for tunnel drainage

Cut & Cover Tunnel Drainage

ABG Deckdrain is a high performance geocomposite drainage system, providing an effective and environmentally friendly alternative to traditional granular structural drainage on cut and cover tunnels and green tunnels. ABG Deckdrain has a high flow capacity and provides added protection to the external walls of the tunnel.

The HDPE cuspated core of the geocomposite provides a free flowing drainage void allowing water to flow in all directions, unlike linear or pipe systems. The cuspates are designed to support the stiffened filtration geotextile which is thermally bonded to the core. This ensures that the geotextile does not deform into the drainage void under the pressure of the backfill material. More information about flow testing.

ABG Deckdrain is durable and sufficiently robust to resist the mechanical stresses imposed during installation and then on throughout its design life. The use of ABG Deckdrain eliminates the need for further protection of the waterproofing system. Deckdrain has been creep tested at compressive loads of up to 1,000 kPa to give a design life of 120 years.

Benefits:

  • Horizontal or vertical drainage applications such as tunnel walls
  • Long term compressive strength up to 1,000 kPa
  • Factory controlled and independently tested flow capacity ensures consistent drainage unlike traditional granular stone methods
  • Enhanced performance of structural waterproofing and additional protection from installation damage
  • Allows use of lower specification backfill
  • Reduced traffic to site when compared with traditional granular stone methods meaning environmental benefits
Cavidrain drainage composites are used in Tunnel cut and cover projects

Click for Tunnel Drainage Projects

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ABG are RISQS Verified - (Railway Industry Supplier Qualification Scheme)

Deckdrain Drainage Geocomposite

ABG Deckdrain is a high performance geocomposite drainage system. Designed to provide an environmentally friendly alternative to traditional structural drainage techniques, it provides high flow capacity and added protection to waterproofing.

more...

Deckdrain drainage geocomposite from ABG Geosynthetics

Cavidrain Protector

Cavidrain® Protector provides a free draining layer to collect infiltration water from behind tunnel linings as well as providing protection from physical damage. 

more...

Cavidrain Protector is a tunnel drainage geocomposite from ABG Geosynthetics

Cavidrain Liner

Cavidrain® Liner is a combined drainage and waterproofing liner that is welded to form an integral waterproof system. The sheets are easily fixed to the smoothed excavated walls with a sealed fixing detail and the system is finished with shotcrete.

more...

Cavidrain Liner is a combined tunnel drainage and waterproofing geocomposite liner

Cavidrain Invert

Cavidrain® Invert provides a pre-formed drainage layer into which the concrete floor slab can be easily cast. Cavidrain® Invert replaces the crushed stone and pipes traditionally used to collect and transport away infiltration water.

more...

Cavidrain Invert geocomposite for tunnel invert drainage
 

Products

Deckdrain Drainage Geocomposite

ABG Deckdrain is a high performance geocomposite drainage system. Designed to provide an environmentally friendly alternative to traditional structural drainage techniques, it provides high flow capacity and added protection to waterproofing.

more...

Deckdrain drainage geocomposite from ABG Geosynthetics

Cavidrain Protector

Cavidrain® Protector provides a free draining layer to collect infiltration water from behind tunnel linings as well as providing protection from physical damage. 

more...

Cavidrain Protector is a tunnel drainage geocomposite from ABG Geosynthetics

Cavidrain Liner

Cavidrain® Liner is a combined drainage and waterproofing liner that is welded to form an integral waterproof system. The sheets are easily fixed to the smoothed excavated walls with a sealed fixing detail and the system is finished with shotcrete.

more...

Cavidrain Liner is a combined tunnel drainage and waterproofing geocomposite liner

Cavidrain Invert

Cavidrain® Invert provides a pre-formed drainage layer into which the concrete floor slab can be easily cast. Cavidrain® Invert replaces the crushed stone and pipes traditionally used to collect and transport away infiltration water.

more...

Cavidrain Invert geocomposite for tunnel invert drainage
 

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