Tunnels and underground structures are essential components of modern infrastructure systems. They provide critical passages for transportation, storage, and utilities distribution. However, these structures are at high risk of water infiltration, leading to severe structural damages, corrosion of steel reinforcements, and compromised safety. Therefore, waterproofing tunnels and underground constructions made of concrete is essential to maintain their longevity and functionality. In this article, we will explore the tips and techniques for waterproofing tunnels and underground structures made of concrete.
Understanding the Causes of Water Infiltration in Tunnels and Underground Structures
Before we delve into the strategies for waterproofing tunnels and underground structures, it is crucial to understand the root causes of water infiltration. In general, there are four primary ways that water can infiltrate tunnels and underground structures:
- Hydrostatic pressure – occurs when water from the surrounding soil exerts pressure on the structure’s exterior walls, leading to cracks and leaks
- Capillary action – happens when water moves through small gaps and pores in the concrete walls due to surface tension.
- Lateral seepage – occurs when water flows through the soil and penetrates through the walls of the structure.
- Condensation – happens when warm, moist air that enters the structure meets the cold surfaces of the underground structure’s interior, leading to the formation of water droplets.
Techniques for Waterproofing Tunnels and Underground Structures Made of Concrete
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Proper Site Preparation – The site should be excavated and thoroughly cleaned to ensure no debris, soil, and other materials that may compromise the waterproofing membrane’s integrity are left. The surface should also be graded to ensure proper drainage.
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Concrete Mix Design – The type of concrete mix design used is crucial in achieving water resistance. The mix should have a low water-cement ratio, high strength, and adequate curing time to promote durability and minimize the chances of cracking.
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Waterproofing Membranes – Application of waterproofing membranes is the most common method used to waterproof tunnels and underground structures. The two most popular types of waterproofing membranes are:
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Liquid Applied Membranes – These are polymer-based products that are applied to the substrate as a liquid and form a seamless, flexible waterproof barrier upon curing. They are easy to apply, fast curing, and can be used to waterproof complex geometries.
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Sheet Applied Membranes – These are premanufactured membranes that are embedded with a reinforcing fabric and come in rolls. They are applied to the substrate by adhering them with an adhesive. They provide excellent resistance to water and require less maintenance than liquid applied membranes.
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Cracks and Joint Sealing – Cracks and joints pose a significant challenge to waterproofing tunnels and underground structures. They can often be the source of water infiltration if not correctly sealed. An effective sealing solution for cracks and joints is the use of injection grouting, which fills the gaps with a waterproofing resin.
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Green Roof Technology – Green roofs are becoming a popular option for waterproofing tunnels and underground structures, particularly for those in urban areas. These are specially designed roofs that are covered with vegetation to insulate, reduce heat gain, and provide a natural waterproofing layer.
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Drainage Systems – Installation of drainage systems around the tunnel or underground structure is an essential requirement in waterproofing. The drain system should be strategically designed to collect and channel water away from the structure’s foundation.
FAQs
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What are the most common methods of waterproofing tunnels and underground structures?
The most popular methods of waterproofing tunnels and underground structures are the installation of waterproofing membranes, sealing of cracks and joints with injection grouting, and installation of drainage systems. -
How effective are green roofs in waterproofing tunnels and underground structures?
Green roofs technology is an effective way of waterproofing tunnels and underground structures. They provide a natural insulation layer, reduce heat gain and absorption, and provide drainage for water runoff.
Conclusion
Waterproofing tunnels and underground structures made of concrete is essential to maintain structural durability, safety, and longevity. Several techniques are available for waterproofing, including proper site preparation, concrete mix design, waterproofing membranes, sealing of cracks and joints, green roof technology, and drainage systems. A combination of these methods is often used to achieve effective waterproofing. By implementing these strategies, infrastructure managers can mitigate the risk of water infiltration and ensure the optimal function of tunnels and underground structures.