Tunnel Waterproofing

Today, operators request a service life for underground structures of over 100 years. However, a lack of watertightness severely reduces the long-term durability of a tunnel structure and poorly affects its planned use, as water ingress and other exposures result in physical attack and deterioration of the concrete. This may result in expensive repair work, damage and even operational downtime.

The selection of the appropriate waterproofing solution, the project specific design of the chosen waterproofing system and its safe application on site are the key elements to minimize operational costs. A waterproofing system typically amounts to a fraction of the total constructions costs. The selection of a high-quality waterproofing solution may easily save an amount of its initial investment or more on future maintenance and repair costs during the entire service life of the structure.

Tunnels face a variety of exposures and stress including water ingress, dynamic forces, temperature variations, chemical and even gas penetration. There are also a variety of methods for excavating tunnels.

All these factors in addition to location, geology and groundwater conditions define the appropriate approach to the tunnel design. The tunnel engineer or designer must understand all factors, prior to defining the construction layout and selecting waterproofing materials and systems.

As the global leader in providing structural waterproofing solutions, Sika has a complete and comprehensive range of solutions and designed systems to meet the specific needs and requirements of owners, architects, engineers and contractors on site.

Sika tunnel waterproofing solutions include:

Highly flexible membrane systems
Liquid-applied polymeric membranes
Waterproofing concrete admixtures
Joint waterproofing systems
Waterproofing mortars and coatings
Injection grouts

For our full range of all tunneling solutions beyond waterproofing, please visit our tunneling solutions webpage.

1. Drained Tunnel (Umbrella)

2. Pressurized Tunnel

3. Cross-Passage Tunnels

4. Cut-and-Cover / Station Box
(Box-in-Box)

5. Cut-and-Cover / Station Box
(Permanent D-Walls)

Pressurized tunnels are under full water pressure, which must be considered in the structural design. The waterproofing layer protects the entire structural concrete against water ingress and chemical attacks.

Selection Table for Pressurized Tunnel Solutions

This method involves the creation of a concrete structure within an existing concrete “box”. The waterproofing layer must be applied before the concreting of the base slab and after the concreting of the top slab. For vertical areas, the waterproofing layer is applied either before or after the concreting of the walls, depending on the site conditions.

Selection Table for Stations Solutions (Box-in-Box)