Ground Anchors - Tunnels

Ensuring excavation and underground structure stability

Ground anchors play a critical role in the safe and efficient construction of tunnels, ensuring the stability of portal walls, access shafts, caverns, cut-and-cover structures, and excavation faces. VSL delivers engineered post-tensioned and passive anchor systems adapted to the geotechnical, logistical, and safety constraints typical of underground works.

The Role of Ground Anchors in Tunnel Construction

Ground anchors provide essential tensile resistance that helps maintain stability throughout the various phases of tunnel excavation and support. They ensure controlled ground behavior, enhance the performance of retaining structures, and contribute to safe working conditions in complex geotechnical environments.

Portal zones are subject to complex load combinations including slope pressures, groundwater uplift, and surface traffic. Ground anchors provide active reinforcement to stabilize retaining walls and excavation support systems, reducing deformation and improving safety margins.

Shafts for ventilation, rescue access, or equipment installation require temporary or permanent support. Anchors increase wall stability, allowing vertical excavation in restricted or urban environments where alternative solutions are not feasible.

Large underground spaces, such as station boxes or utility caverns, need robust support to manage rock mass behavior and convergence. Anchors ensure stability during sequential excavation and long-term operation.

In water-saturated zones or where pressure relief is needed, anchors counteract uplift forces acting on slabs or linings, preventing structural displacement.

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VSL’s Ground Anchor services for tunnels

VSL provides complete ground anchor solutions, from design and supply to installation, testing, and monitoring. Our systems comply with international standards and are adapted for underground construction environments.

Temporary and permanent anchor systems

• Temporary anchors for excavation phases, designed for movement control and ease of de-tensioning.
• Permanent anchors with multi-layer corrosion protection for long-term stability of portals, shafts, and tunnel-related structures.

Post-Tensioned Ground Anchors

Using VSL’s proprietary tendon systems, post-tensioned anchors are stressed to the design load and individually tested to confirm performance, following the same standards used in building and infrastructure anchor works.

Drilling, grouting and execution

VSL installs anchors in all ground types using:
• Rotary or rotary-percussive drilling
• High-quality primary and secondary grouting
• Hole flushing and cleaning adapted to underground conditions
• Head assembly configured for restricted access zones

Acceptance testing and monitoring

Every anchor undergoes proof testing and, where required, creep or performance tests. For permanent systems, VSL offers load monitoring and periodic inspections to support asset management.

Why choose VSL for tunnel Ground Anchors?

  • Integrated design and execution

    VSL supports geotechnical engineers and contractors from early feasibility through execution, ensuring optimized anchor length, load levels, corrosion protection, and constructability.

  • Reliable, high-performance systems

    VSL anchors use high-strength steel strands or bars, advanced corrosion protection layers, and controlled grouting to meet international durability requirements.

  • Experience in confined and complex tunnel environments

    Our teams are trained to operate in restricted access spaces, high groundwater zones, steep portal slopes, and urban constraints, minimizing impact on ongoing works.

  • Proven track record across infrastructure and underground works

    VSL has delivered thousands of anchors worldwide for deep excavations, transport tunnels, and rock stabilization projects.

FAQs about Ground Anchors

These are some of the most common questions we receive. Got another one? Reach out to us!

Typically post-tensioned strand anchors for high capacity, bar anchors for shorter lengths, and passive anchors where preloading is not feasible.

Yes. VSL adapts drilling methods and grouting procedures to soils, fractured rock, or water-bearing strata.

With appropriate corrosion protection, anchors can last for the full design life of portal walls or tunnel structures.

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Looking for engineered anchoring solutions for your tunnel project?

Contact VSL to discuss design, execution, and performance requirements.