The ground freezing method—often also referred to as ground freezing or artificial ground freezing—is a geotechnical technique in which water-bearing or low-bearing-capacity soil is purposefully cooled until it solidifies into a temporarily load-bearing and impermeable mass. This enables work below the groundwater level, controls inflows, and allows excavation pits, shafts, or tunnels to be opened safely. In practice, freezing often creates the conditions for precise, low-vibration working methods in deconstruction and advance excavation. This makes it easier to plan the use of hydraulic rock and concrete splitters or concrete demolition shears from Darda GmbH in sensitive environments: water ingress is limited, stability is increased, and cutting and splitting operations become more predictable and cleaner.
Definition: What is meant by the ground freezing method
The ground freezing method is a temporary stabilization and sealing technique in which the pore water in the soil is frozen into ice using refrigerants. The resulting structure of soil and ice—the so-called frozen body—increases strength and stiffness, reduces permeability, and serves as a load-bearing, watertight construction aid. Two main variants are widely used: the brine method with circulating, cooled saline solution and the nitrogen method with evaporating liquid nitrogen. Both create a closed, load-transferring frozen body through heat extraction, which is built up step by step, monitored, and carefully thawed after completion of the work.
Technical operating principle and variants of the ground freezing method
Heat is extracted from the ground via freeze pipes installed in the soil until the pore water freezes and a continuous ice body develops. In the indirect brine method, a highly cooled saline solution circulates in a closed loop; in the direct method using liquid nitrogen, heat extraction occurs through nitrogen evaporation. The choice and design depend on geology, groundwater conditions, required freezing thickness, construction schedule, and environmental conditions. Precise temperature and deformation monitoring documents the growth of the frozen body and controls the construction process. Once the required thickness and temperature are reached, earthworks and demolition works begin under the protection of the freezing—often in combination with low-vibration tools such as concrete demolition shears or stone and concrete splitters from Darda GmbH, for example when removing linings or creating breakthroughs near sensitive structures.
Fields of application in construction, deconstruction and special foundation engineering
The ground freezing method is used wherever water ingress, low soil strength, or stringent settlement limitations are present. Typical fields of application align with the working domains of Darda GmbH:
- Rock excavation and tunneling: Sealing the tunnel face and shaft, temporary stabilization of loose ground in the heading, construction of cross-passages.
- Concrete demolition and special demolition: Safe access to foundations and basements below the groundwater table, controlled opening of excavation pits adjacent to existing structures.
- Building gutting and cutting: Freezing as a protective measure against water and contamination in partial areas to make cutting and separation work predictable.
- Natural stone extraction: Temporary stabilization of water-bearing joints to decouple splitting operations in rock.
- Special deployment: Temporary sealing of small cavities, emergency measures for unforeseen water inflows.
Interfaces to stone and concrete splitters and concrete demolition shears
Freezing functions as a construction aid that optimizes the environment for force- and control-based methods. This creates direct interfaces to tools from Darda GmbH:
Low-vibration operation
In frozen ground, water ingress is limited and stability increases. As a result, stone and concrete splitters can open cracks in a targeted manner and loosen blocks without additional securing measures. Concrete demolition shears grip more precisely because the work area remains dry, clean, and load-bearing.
Breakthroughs and deconstruction near groundwater
When deconstructing basements, shafts, or tunnel linings, the frozen body enables openings in wall or base slab areas. After the initial cut, concrete demolition shears, combi shears (HCS8), and multi cutters can separate and remove sections in a targeted manner—without water mist and with reduced debris load.
Protecting the surroundings
The combination of freezing and hydraulically driven tools reduces vibrations. This protects adjacent structures and sensitive infrastructure and helps to comply with vibration and noise limits.
Planning and sequence: from feasibility to thawing
- Feasibility study: geology, hydrogeology, temperature and heat balance, construction sequence.
- Design: pipe spacing, freezing thickness, cooling capacity, redundancies, monitoring concept.
- Installation: drilling, installation of freeze and measurement pipes, pressure and leakage tests.
- Freezing phase: commissioning the cooling system, temperature monitoring, documentation.
- Work phase: earthworks and demolition works under the protection of the frozen body, e.g., splitting and shearing operations coordinated with daily output and permissible temperature windows.
- Thawing phase: controlled shutdown, temperature and settlement monitoring, removal of auxiliary installations if necessary.
Choosing the method: brine or liquid nitrogen
The brine method offers continuous, well-controllable freezing for longer deployment periods. The nitrogen method provides very high cooling rates and is suitable for rapid, locally confined measures or emergencies. Criteria include required freezing time, desired duration of stability, excavation geometry, heat sources (e.g., groundwater flow), and emission requirements. The decision is often driven by schedule and logistics as well—for instance, when deconstruction crews with concrete demolition shears have a fixed time window.
Material behavior of soil, rock, and concrete under frost
When freezing, ice forms a rigid bridge within the pore space. Cohesion and stiffness increase, permeability decreases. In hard rock, freezing stabilizes jointed zones and reduces water ingress. In concrete, freeze–thaw effects must be considered: a permanently frozen contact zone is mechanically favorable, whereas repeated freezing and thawing may weaken surfaces. For work planning this means: splitting and shearing operations are scheduled within the stable temperature window to achieve clean fracture surfaces.
Occupational and environmental safety
Handling refrigerants requires clear protective measures. Cold burns, oxygen displacement when using nitrogen, noise, and energy consumption must be considered. Groundwater is sealed off by the frozen body; nevertheless, inflows, possible diversions, and settlement risks must be monitored. Permitting issues are clarified on an object-specific basis and depend on local requirements; statements here are general and do not replace case-by-case assessment.
Quality assurance and monitoring
Central measures include temperature measurements along the measurement pipes, geophysics where applicable, and deformation measurements. Target values are minimum temperatures within the frozen body, sufficient overlap, homogeneous thickness, and threshold values for settlements. Documentation must be kept so that demolition and separation teams—e.g., when using stone and concrete splitters, concrete demolition shears, steel shears, or tank cutters—can safely align their workflow with the stability windows.
Practical guidance for combined use with demolition technology
- Keep weather-suitable hydraulic fluids and hydraulic power units on hand to compensate for viscosity effects in the cold.
- Preheat tools and check seals; cold materials exhibit different fracture behavior.
- Plan the sequence of cuts and splits so that load-bearing areas of the frozen body are preserved until the end.
- When using multi cutters, steel shears, and concrete demolition shears: plan chip and fragment management for brittle material.
- For tank cutters: ensure contents and atmospheres are secured by qualified means; freezing can serve as an additional protective measure but does not replace inerting or gas clearance testing.
Limits, risks, and alternatives
Very high groundwater flows, highly saline water, or significant heat sources can impede the formation of a closed frozen body. Energy demand is relevant, and logistics and supply must be assured. Alternatives include injection sealing, sheet pile walls, or underwater concrete. A combination is often sensible: freezing for the critical phase, followed by conventional excavation support—with a seamless transition to separation methods such as concrete demolition shears or stone and concrete splitters.
Cost-effectiveness and scheduling
Costs are determined by drilled meters, cooling capacity, deployment duration, monitoring effort, and site logistics. Predictable, water-free work windows accelerate splitting and shearing operations and reduce rework. Schedules tightly couple freezing with the takt units of the deconstruction crews to minimize idle times and make optimal use of temperature windows.
Typical sources of error and how to avoid them
- Insufficient investigation: leads to gaps in the frozen body. Remedy: additional probing, close-meshed monitoring.
- Opening too early: starting work before target temperatures are reached. Remedy: rigorously enforce release processes.
- Inappropriate tool selection: vibration-intensive methods in sensitive environments. Remedy: rely on hydraulic, low-vibration tools such as concrete demolition shears.
- Unwanted thawing: heat input from open water or machinery. Remedy: enclosures, takt planning, thermal protection.