Tunnel waterproofing is critical for the long-term integrity of subterranean infrastructure. Our injection systems are engineered to deliver targeted solutions for both new and existing tunnels, using advanced grouting and resin technologies to seal joints, fill voids, and mitigate water ingress. Whether applied as a preventive measure or remedial solution, these systems strengthen the tunnel lining and enhance durability against aggressive groundwater conditions. Backed by proven performance in global infrastructure projects, the injection systems by ADCOS Asia ensure reliable, cost-efficient protection for government and civil engineering works across Singapore.

Why Do Tunnels Leak?

Tunnels can experience leakage due to several factors that compromise their tunnel waterproofing. Understanding the underlying causes can help prevent further damage and improve the longevity of tunnel infrastructure.

Water Table Fluctuations

High groundwater levels can lead to water seepage into tunnels, especially if the waterproofing systems degrade over time.

Structural Settling

As tunnels settle, gaps can form, allowing water to penetrate through cracks and joints.

Poorly Sealed Joints

If tunnel joints are not properly sealed during construction, water can easily infiltrate these areas.

Ageing Materials

Over time, the materials used in tunnel construction, such as concrete and waterproof membranes, may deteriorate, increasing the risk of water leaks.

External Pressure

Pressure from surrounding soil or construction activities can lead to fractures in tunnel linings, making them susceptible to leaks.

Challenges in Tunnel Waterproofing

Implementing effective tunnel waterproofing solutions presents a range of engineering and environmental challenges. Tunnels are continuously exposed to hydrostatic pressure, shifting ground conditions, and groundwater fluctuations—all of which contribute to water ingress over time.

Inadequate sealing of joints, ageing concrete linings, and compromised membranes further increase vulnerability. Chemical contaminants, vibration from nearby works, and access restrictions complicate both inspection and repair. These conditions are especially prevalent in urban infrastructure and transport tunnels where operational continuity is critical.

As such, waterproofing systems must be engineered to accommodate complex site conditions while offering long-term resilience. The choice of injection material, method, and compatibility with the tunnel structure plays a vital role in determining performance and durability.

Injection Solutions Based on Tunnel Types

Injection systems for tunnel waterproofing are selected based on tunnel design, construction method, and operating environment. Below are common methods matched to their ideal applications:

Polyurethane Injection (PU) – For Water-Bearing Tunnels

Ideal for live water ingress, PU resins react upon contact with moisture to expand and seal active leaks. Commonly used in metro, sewer, and underpass tunnels where rapid sealing is needed.

Acrylic Resin Injection – For Fine Cracks and Porous Areas

With low viscosity and deep penetration, acrylic resins are effective for curtain grouting behind tunnel linings. Suitable for bored tunnels and diaphragm wall interfaces.

Cementitious Injection – For Structural Stability in Concrete Tunnels

Best applied in cast-in-situ or segmentally lined concrete tunnels, cementitious grouts bond strongly with existing substrates, enhancing structural support and waterproofing simultaneously.

Epoxy Resin Injection – For Structural Repairs in Load-Bearing Zones

Recommended for restoring structural integrity in damaged zones. Epoxy’s high compressive strength and resistance to chemicals make it ideal for utility tunnels and technical galleries.

Key Advantages of Injection-Based Tunnel Waterproofing

Injection technologies offer multiple benefits tailored to civil and government tunnel projects in Singapore:

Comprehensive Waterproofing

Injection systems seal leaks at their source, forming continuous barriers that reinforce tunnel waterproofing performance even under fluctuating pressure conditions.

Non-Invasive Application

Installation can be carried out from within the tunnel, requiring minimal excavation or structural modification. This makes it highly suitable for operational environments like MRT systems.

Fast and Scalable Response

From small-scale repairs to full rehabilitation, injection systems allow for quick mobilisation and scalable implementation, ideal for urgent government maintenance projects.

Durability and Compatibility

Formulated to withstand aggressive groundwater, chemical contaminants, and mechanical stress, our injection materials maintain integrity across a wide range of tunnel applications.

Cost Efficiency

Compared to full membrane replacement or re-lining, injection-based tunnel waterproofing offers a lower total cost of ownership while minimising tunnel downtime.

Tunnelling Injection Systems