Left: Synthetic sheet
waterproofing membrane placement to tunnel profile
The first half of the workshop focused on why
waterproofing is needed, the requirements of water tightness, types of waterproofing solutions in tunnels, durability, and then concluded with the topic of innovations. At its essence, waterproofing within tunnels is
required to prevent water inflow and to protect the tunnel lining from degradation due to mechanical failure of the reinforced concrete lining. An early investment in a reliable waterproofing system can prevent huge maintenance and repairs costs possibly incurred later in the asset lifetime due to damages from water ingress. Here, Sarah presented some dramatic examples of significant water damage to tunnels which drove the point home. One of the cornerstones of designing waterproof
systems is understanding the different design influences on product selection. These include the depth of the system below ground in conjunction with the water table level, the soil conditions, presence of ground
contaminants, temperature, construction methods, and standards, to list a few. The other cornerstone is understanding the level
of watertightness that is needed by the client for the infrastructure asset. The Swiss standard SIA 272/197 covers material and waterproofing requirements for geomembranes used in tunnels, and it provides classes for watertightness and the types of tunnels they commonly apply to. This is further, numerically elaborated in performance terms by the STUVA Report which provides the permitted rate of water infiltration, in litres/m2
for a duration of 24 hours. Following the first steps of the design process,
Sarah proceeded to explain the different waterproofing solutions available, depending on the type of tunnel and the watertightness required. For mined tunnels, the waterproofing options
are: synthetic sheet membrane systems; watertight segmental lining; sprayed tunnelling membrane; and, watertight concrete (white box concept).
Left:
Compartment-based waterproofing system
December 2023 | 11
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53
