Horizontal Directional Coring - Tunnels

A single hole to recover relevant ground properties data all along a planned trajectory

Underground tunnel projects, whether for roads, rail, or metro systems, depend on accurate ground profiling to inform design, installation, and tunneling method selection. Horizontal Directional Coring (HDC) delivers continuous geological data along the planned tunnel alignment, addressing adverse soil conditions and unexpected faults that could disrupt a Tunnel Boring Machine (TBM) launch or progress.

Why ground profiling matters

Ground profiling is essential for anticipating subsurface conditions and ensuring tunnel design and construction proceed safely, efficiently, and without unexpected geological surprises.

Continuous coring identifies soil heterogeneity, groundwater presence, and faults, preventing TBM downtime.

Accurate geological profiles support refined tunnel trajectory, reducing construction costs and delays.

A single HDC hole can provide more meaningful data than tens of conventional bore.

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VSL’s Horizontal Directional Coring service

VSL provides end-to-end Horizontal Directional Coring (HDC) services that deliver continuous geological insight along tunnel alignments, enabling safer design and more predictable excavation.

Design & engineering

Engineering begins with trajectory planning to target critical zones along the tunnel route. Data from initial surveys informs the coring plan and drilling setup.

Coring execution

VSL’s specialized HDC equipment extracts continuous cores along the full trajectory, even where conventional rig access is limited. This delivers continuous ground stratigraphy, including shear zones and groundwater-bearing layers.

Geotechnical analysis & reporting

Recovered cores undergo lab testing for soil classification, strength, and permeability. Results are compiled into a geotechnical report detailing stratigraphy, fault zones, and construction recommendations.

Why Choose VSL for Horizontal Directional Coring?

  • Proven expertise

    VSL is recognized for ground engineering solutions in complex conditions, leveraging post tensioned tendons, FRP reinforcements, and hydrodemolition where needed.

  • Efficient, turnkey delivery

    We manage the full process, from design through lab analysis, via our in house HDC systems.

  • Global experience

    Deployed on major tunnel projects worldwide, including metro and road applications.

  • Continuous core recovery in complex ground

    VSL’s HDC systems are designed to recover undisturbed, full-length core samples along horizontal alignments, including through mixed ground conditions and low cover zones where vertical drilling is impractical.

FAQs about Horizontal Directional Coring

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

HDC provides continuous core samples along tunnel direction, offering superior geological resolution compared to isolated vertical bores.

Depends on tunnel alignment. Typical runs are [placeholder length]; please consult VSL for project-specific planning.

Yes, cores reveal groundwater-bearing strata and fault shear zones, critical for tunnel lining and TBM planning.

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You’re planning a tunnel project and you need precise ground profiling?

Contact VSL today, our specialists will assess your route and provide a tailored HDC solution.