Enhance Safety and Longevity with Tunnel Waterproofing

When it comes to tunnels, galleries, and shafts, one of the most effective ways to enhance safety, functionality, and lifespan of these structures is through proper waterproofing. Without adequate waterproofing, water seepage can cause damage through freeze/thaw action, posing a risk to block and cast work. Signs such as spalling concrete or block, icicles, and efflorescence or stalactites are clear indicators of a tunnel with either no waterproofing or an inadequately designed system.

It is crucial to optimize not only waterproofing but also ventilation, lighting, and emergency stations to ensure the highest level of safety and convenience for users. Combining these elements can achieve the greatest degree of comfort and convenience.

Crucial Safety Measure

Waterproofing tunnels is an essential safety measure that eliminates the risk of water seeping through the structure and freezing on the road or track surfaces. This, in turn, prevents accidents and ensures that traffic can pass through safely. Additionally, waterproofing prevents the spilling of poured concrete or concrete blocks due to freeze/thaw action, which can also pose a safety hazard.

By eliminating these risks, routine maintenance work can be performed with greater security, and the proper operation of electrical, lighting, and ventilating systems contained within the structure is ensured. Furthermore, waterproofing prevents the long-term effects of water incursion, such as the leaching of lime and minerals from concrete and mortar and the corrosion of reinforcing elements, which can compromise the tunnel’s structural integrity.

By investing in waterproofing, special maintenance due to untimely deterioration of the structure is virtually eliminated, and the structure is able to function as designed over long periods of time, making it a sound economic decision.

PVC waterproofing membranes are a popular choice due to their high resistance to aging and excellent elongation and tensile characteristics. They offer a secure and leak-free installation when applied and seamed correctly. The key benefits of PVC tunnel membranes are:

• Aging and Rot Resistance (Even Under the Influence of Water Containing Aggressive Elements)
• High Mechanical Strength and Load Resistance
• Sensible and Effective Installation

Selecting the appropriate waterproofing system for tunnels depends on several factors, including the type and construction of the tunnel and the geological conditions. When dealing with tunnels through rock, the focus is usually on addressing seepage through cracks in the rock, which does not involve a significant head of water. In such cases, partial or umbrella waterproofing is applied specifically to the vault. 

However, tunnels in friable or loose rock often face challenges, such as springs and water flowing through the strata. To tackle these conditions, it is necessary to fully wrap the tunnel with waterproofing material that is specifically designed to withstand the expected hydrostatic pressure.

It is important to pay close attention to the installation and welding of PVC membranes to ensure the longevity of the waterproofing system. The size of the membrane is determined by the shape and size of the structure and is delivered to the job site in rolls or prefabricated panels.

Seams are produced either by hot air or hot wedge welding, depending on the type of seam specified. The welding equipment can be adjusted to allow for temperature and humidity conditions on the site.

The sheets are loosely laid and do not require the substrate to be dry, which can be the deciding factor in choosing the type of waterproofing in areas with continuous water seepage through the rock or where open cut construction exposes the lining to weather for long periods. The leveling layer, composed of a non-woven geotextile mat or drainage fabric, is an indispensable element in the waterproofing system.

Materials

It is important to ensure that all materials used in the system, including concrete, are compatible to ensure that the material properties of age resistance, elongation, and tensile strength will last for years.

WA-Anchor System

• Description:
• The WA-Anchor system is composed of a prefabricated PVC element, a PVC membrane, and a steel anchor.
• Field Application:
• The WA-Anchor system is widely used in tunnel construction to support the dead load of the reinforcement in the final lining.
• Advantages:
• High Load Transfer Through the PVC Element, Enhancing the Strength of the Shotcrete Lining
• Superior Waterproofing Around the Steel Anchor Area
• Corrosion Protection for the Steel Anchor
• Easy and Fast Installation Process