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Frost‑covered industrial pipes and valves at a processing facility, with gauges and metal fittings surrounded by thick layers of ice.Frost‑covered industrial pipes and valves at a processing facility, with gauges and metal fittings surrounded by thick layers of ice.

Ground Freezing

Ground freezing is a safe and environmentally friendly method for making water-saturated soils stable and watertight. We design and implement artificial freezing reliably, efficiently, and with many years of experience.

Ulrich Lange

Practice Lead

Ulrich Lange

Contact Ulrich

Ground Freezing - Stability for Challenging Soil

Anyone who has tried digging a deep hole in dry sand knows the problem: the sides collapse. Damp sand is more stable, and in winter frozen sand can even form vertical walls.This principle is applied by engineers working in tunnelling, specialist foundation engineering and mining.
Ground freezing uses double-walled pipes (“freezing lances”) inserted into the soil. A pump forces the refrigerant downwards through the inner pipe for it to rise back up again in the outer pipe, drawing heat from the surrounding soil. This results in frozen cylindrical forms around each freezing lance. The longer the process continues, the larger these frozen cylinders become, increasing stability in the loose soil while making it more impervious to water.

Ground Freezing Methods

Depending on site conditions, two main methods are applied:

  • Brine Freezing: A special salt solution (brine) with temperatures of up to -35 °C serves as the refrigerant.
  • Liquid Nitrogen Freezing: If a frozen body needs to be established quickly, liquid nitrogen is used.

However, the liquid nitrogen evaporates as it passes through the freezing pipes. Unlike brine freezing, which requires a refrigeration unit to cool the brine after heat extraction, nitrogen freezing requires a continuous supply of nitrogen from tanks. This makes the method very costly over extended periods.

Sometimes, both methods are combined: the frozen body is initially formed quickly with nitrogen and then maintained using brine freezing.

Good To Know

The refrigerant circulates in a closed loop and does not enter the soil. Ground freezing is used in difficult soil conditions for deep excavations, tunnels, and shafts. In urban areas, it has proven particularly effective in recent years. For freezing without additional measures, the soil must have a sufficiently high-water content and allow only slow groundwater flow.
Construction site with two tunnel entrances, surrounded by pipes and orange safety cones.
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Ground Freezing Projects Worldwide

Our Services

We support your ground freezing project from the initial concept to safe implementation – technically sound and from a single source:

  • Freezing Structures: Planning and supervision of tunnel, excavation, and shaft freezing
  • Methods: Execution of brine and liquid nitrogen freezing – according to project requirements
  • Finite Element Calculations: Accurate numerical simulations for freezing design
  • Laboratory Investigations: Laboratory investigations in our own freezing lab
  • Consulting, Planning, Structural Analysis, and Thermal Design
  • Construction Supervision & Monitoring: Technical oversight throughout the execution phase
Drei Bauingenieur*innen mit Schutzkleidung überwachen die Baustelle

Reliable Freezing, Minimised Risk

From analysis to monitoring, we develop robust, efficient and precise ground freezing concepts – tailored to the specific requirements of your project.

CDM Smith’s Ground Freezing Lab

Our in-house freezing laboratory in Bochum, Germany provides fast and precise measurement data for frozen and thawed soil samples.

Over 30 Years of Global Experience

CDM Smith experts have carried out numerous ground freezing projects around the world. Our internal database provides reliable soil and thermal parameters for freezing soils.

On-Site Design Consultant

We offer a complete package: from subsurface investigations and geotechnical reports to thermal calculations, comprehensive consulting, and construction supervision.

Person in a gray suit with a white shirt stands by a white brick wall.
Person wearing a dark suit and white shirt indoors.
Person in dark suit and light blue shirt standing in a modern indoor setting.

Ground freezing is an environmentally friendly technique: The refrigerant remains within an entirely closed system and no chemicals are injected into the ground. Afterwards the soil is left to thaw out without leaving a trace.

Sven Kessler

Ground Freezing Expert

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Project Manager specialised in ground freezing, with extensive expertise in geotechnics, foundations and ground improvement.

Ground freezing provides an effective and sustainable solution to complex challenges in specialised foundation engineering.

Ulrich Lange

Senior Business Development Manager

Contact Ulrich

Dr Ulrich Lange manages national and international projects in ground freezing and mining.

Our in-house freezing laboratory enables us to obtain reliable data quickly. This accelerates planning and increases the reliability of the calculations.

Simon Klösges

Ground Freezing Expert

Contact Simon

Project manager for national and international infrastructure projects, specialising in shaft and tunnel construction and ground freezing.

Our Projects

Our experts deliver reliable ground freezing solutions worldwide, making even complex subsurface conditions manageable.

Construction site with two tunnel entrances, surrounded by pipes and orange safety cones.
Construction site with two tunnel entrances, surrounded by pipes and orange safety cones.
Perth, Australia

Ground freezing at Forrestfield Airport in Perth

For the “Forrestfield Airport Link” CDM Smith executed freezing tests from which we determined thermotechnical and static parameters for the frost body sizing.

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Leaning Tower of Pisa with cathedral, blue sky, and grassy foreground.
Leaning Tower of Pisa with cathedral, blue sky, and grassy foreground.
Pisa, Italy

Leaning Tower of Pisa

The Leaning Tower of Pisa is one of the world’s most famous landmarks and was extensively restored and stabilised with the support of CDM Smith.

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Paris Metro train crossing a historic bridge beside ornate buildings.
Paris Metro train crossing a historic bridge beside ornate buildings.
Paris, France

Ground freezing for the Grand Paris Express

CDM Smith analysed soil samples and advised contractors on design and the best method for ground freezing at a major French infrastructure project.

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Our services 

Discover what we do and explore the projects that showcase our capabilities.

Tunnelling

We combine detailed planning with smart solutions to master even the most complex ground conditions.

Geotechnics

From ground investigation to execution: Our geotechnical experts support you in every project phase with in-depth know-how and innovative methods.

Special Foundation Engineering

Every construction project needs a solid foundation – we deliver special foundation and geotechnical engineering solutions for stability, safety and long-term performance.

Infrastructure

Forward-looking infrastructure starts with planning expertise: We assess feasibility, evaluate risks, and develop the best solutions for your project.