Tunnel Waterproofing Systems



The choice of a waterproofing system depends upon the type and construction of the tunnel as well as the geological criteria. Tunnels through rock generally deal only with seepage through cracks in the rock, a condition in which there is no head of water. In these cases, waterproofing is applied only on the vault. This is called partial or umbrella waterproofing. In the case of tunnels in frable or loose rock, however, one often encounters springs and water running through the strata. These conditions require the tunnel to be fully wrapped in waterproofing material designed to withstand the expected hydrostatic pressure.


Application Rock Tunneling / Umbrella System

hydrostatic condition no hydrostatic pressure, ground water level is below tunnel footings
tunnel wall condition uneven
substrate structure shotcrete min 3" thick
waterproofing

geotextile/ drainage layer nailed at intervals onto tunnel wall using PVC-disk, 2pcs/sq.ya.

membrane 1.5mm, 2.0mm, 2.5mm, 3.0mm welded to pvc-disk. Joints welded by hot wedge machine or hot air.

inner lining cast in place concrete or shotcrete

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Application Soft Ground / Closed System

hydrostatic condition hydrostatic pressure, ground water level is within tunnel area
tunnel wall condition even
substrate structure shotcrete, concrete segments
waterproofing

geotextile/ drainage layer nailed at intervals onto tunnel wall using PVC-disk, 2pcs/sq.ya.

membrane 1.5mm, 2.0mm, 2.5mm, 3.0mm welded to PVC-disk. Joints welded by hot wedge machine or hot air.

water barrier welded to membrane as required

inner lining cast in place concrete or shotcrete

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Application Cut & Cover / Umbrella or Closed System

hydrostatic condition hydrostatic pressure or no hydrostatic pressure
tunnel wall condition even
substrate structure clean, smooth, cast in place concrete
waterproofing

geotextile/ drainage layer nailed at intervals onto tunnel wall using PVC-disk, 2pcs/sq.ya.

membrane 1.5mm, 2.0mm, 2.5mm, 3.0mm welded to PVC-disk. Joints welded by hot wedge machine or hot air.

water barrier welded to membrane as required.

inner lining cast in place concrete

> pictures <