Ground freezing for retaining walls and groundwater control in civil works

Waterproof stabilization
in all ground conditions
Geofrost structures are safe and environmentally friendly in addition to beeing economically competitive.
CONSULTANT AND CONTRACTOR.
Specialized in AGF since 1986.

Benefits

Any ground condition

Geofrost ground freezing works in all kinds of soil, independent of grain size distribution, permeability and water content. It works in soils, such as moraine, glacifluvial deposits, peat, land fills and rocks of various quality. This makes Geofrost ground freezing work equally well for transition zones between soil and rock and for soil containing boulders, with a 100 % waterproof result.

100 % waterproof

  • Full control of water inside and outside the Geofrost walls.
  • No wash out of fines with corresponding risk for instability and sink holes.
  • No leakage leading to pore pressure reduction and settlements.
  • No need for water infiltration and associated risk.
  • No extra sealing with cement or chemicals.
  • No influence zone outside the frost construction.
  • Installation from above groundwater level provides 100 % ground water control even from before starting the excavation.

Efficient excavation to significant depth

The Geofrost wall's capacity is increased by increasing thickness, enabling great depths without stiffeners or anchors. The earth support is ready when excavation starts, enabling countinous excavation without interuption for shoring or support.

Any geometry

The freezing pipes are freely positioned, with any inclination, so the earth support gets the required shape. As long as you can drill, you can freeze.

Although the freezing pipes are placed individually, a continous construction is established between them. The frozen body can therefore easily be established across railway tracks, pipes and cables and provide a waterproof sealing around bodies crossing through the wall. The Geofrost wall also becomes waterproof towards uneven surfaces of materials such as rock, steel, wood, concrete, plastic, etc.

Moderate energy consumption

Production of construction materials requires energy, either if it is freezing soil or it is producing steel or concrete. A comparison between sheet piles and Geofrost walls shows that the energy consumed by freezing over half a year is equivalent to just producing the steel for GU6N sheet piles. Almost two years of freezing is equivalent to producing the steel for AZ48 sheet piles. Comparing pile wall of steel pipes, Ø406x10mm, freezing can last nearly 3 years before consuming the same amount of energy.

Products

Geofrost's products aid in stabilization and/or waterproofing temporary excavations, specially below the groundwater table.

Construction pit

Figure: Construction pit with Geofrost walls.

We deliver temporary construction pits in a wide variety of depths and shapes, with both floating and cantilever design. Independent of ground conditions, Geofrost's construction pits are completely waterproof, towards an impearmable layer, a frozen bottom or a constructed bottom. This provides excellent groundwater control and unaffected pore pressure for soils sensitive to settlements outside the pit.

Photo: Excavation of construction pit stabilized by Geofrost ground freezing.
The frost construction is designed according to the Eurocode and deformation requirements set. Thickness and geometry is adjusted to provide required capacity. The Geofrost walls are usually established without stiffeners, enabling continous and efficient excavation.

Bottom seal - Impermeable bottom

Figure: Excavation of construction pit stabilized with ground freezing and with waterproof frozen bottom.

When a waterproof construction pit is required and it is deep to a sufficiently impermeable layer below the excavation depth, Geofrost provides a waterproof layer, attached to the walls, whether they are sheet piles, secant piles or frozen walls. Frozen soil has good adhesion to other construction materials, like steel, wood and concrete and makes a completely waterproof connection. The Geofrost bottom is made from surface so the pit is sealed when excavation starts and is designed against the water pressure below the bottom and the buoyancy of the whole pit.

Deep construction pits below groundwater table with waterproof bottom are made sufficiently heavy to ensure buoyancy balance, making bouyancy anchors superflous, unless required by the permanent situation.

100 % waterproof construction pit eliminates dewatering and pore pressure reduction in the surrondings and associated risk for settlements.

Retaining wall

Figure: Cantilever Geofrost wall fixed in bedrock.

Photo: Insulation of Geofrost wall.
Geofrost delivers temporary stable and waterproof retaining wall, anchored in rock. The walls are established by drilling down to rock and install freezing pipes inside the casing.

The Geofrost walls are particularly suitable in frictional soils containing stones. It is easier to drill single holes through moraine, tallus, rock fill or even ancient quay structures than to put down a continous construction. Ground freezing makes the retaining structure continous between the single holes drilled.

Photo: Geofrost walls crossing tram tracks in use.
Cables crossing the location of the supporting structure are often rerouted in own preparatory contracts. Geofrost retaining walls can be established continously across tracks, cables and pipelines, which should be in continous operation. By using Geofrost walls, the preparatory rerouting may be skipped.

Underpinning

Figur: Frost som midlertidig understøttelse av hus.

Geofrost delivers temporary underpinning of foundations and structures adjacent to deeper excavations or where the foundation needs to be repaired.

Foto: Frostvegg under fundament.
Freezing pipes are installed in holes drilled vertical next to the structure to be underpinned, and the frost will penetrate horizontally underneath the structure. A good load transfer is enabled without any intervention in the construction to be underpinned, and is removed by thawing after use.

If foundation walls are to be extended from existing level to a deeper level, the frost structure is made wide enough to enable cutting into it without loosing the stabilizing or waterbarrier effect. Secton by section may then be excavated and the foundation repaired or extended.

Soil anchor

Soil anchors made of frozen cylinders have a large diameter with perfect friction against the surrounding soil, and therefore can be delivered with high capacity. Geofrost soil anchors can be established in all ground conditions, but higher capacities are reached below groundwater level. The frozen shoring can be combined with different retaining walls and is maintained as long as needed.

Ground improvement

Figur: Grunnforsterkning ved grunnfrysing,

Geofrost delivers temporary construction road foundation on unsupporting underground like soft clay, quick sand, swamp and in winter climate even on water.

Foto: Pelemaskin på frostforsterket underlag.

Geofrost ground improvement may also be used for temporary access across vulnerable land that needs protection against mechanical wearing.

Groundwater control

Figur: Vanntetting av spunt med frost, ved hjørne og overgang til berg.

Geofrost walls provide optimal groundwater control in connection with underground works. The excavation pit may be 100 % sealed against pore pressure drop outside the construction pit, reducing the area of influence to the border of the frozen structure. Settlements in the surroundings due to pore pressure reduction are avoided.

Geofrost retaining walls are established from above the groundwater table, not affecting the pore pressure. This will also be the case for supplementary waterproofing to other retaining walls or structures. Examples are sheet piles not driven in lock in the corner, or run out of lock during installation, space between sheet pile and rock, water barrier further down through fractured rock. Ground freezing may also seal secant pile walls where some columns have been driven out of the straight vertical pattern, or jet grouting piles that have some permeable sections.

Ground freezing is adhering well to other construction materials and may very well be combined with steel, concrete or timber. Frozen ground seals against all materials and irregularities. In soil, ground freezing is the best method to ensure complete groundwater control.

Cofferdam

Figur: Geofrostvegg gjennom sprengsteinsfylling i vann, for etablering av fangdem.

If a cofferdam solution is choosen, Geofrost can provide an impermeable core in a rock fill dam. This will ease the establishment because a sheet pile penetrateable core will not be needed. Freezing pipes are installed in cased holes drilled from surface and penetrating as far down through impermeable layers and fractured rock as the impermeable core is needed, enusring a completely impermeable cofferdam.

What we deliver

We are a total supplier of retaining walls and impermeable construction pits by ground freezing and offer all related services within design and construction as well as ground investigation with undisturbed soil sampling of frictional soils and lab testing.

We deliver temporary support for conststruction pits, ditches and shafts, groundwater control and ground improvement, ready designed and installed, or part of it customized to the client and project.

Consulting

  • Project management
  • Sampling
  • Lab testing
  • Design and engineering
  • Numerical analyses
  • Design report, drawings and specifications

Contracting

  • Planning and procurement
  • Site management
  • Drilling and surveying
  • Pipe installation
  • Plant and equipment for brine freezing and nitrogn freezing
  • Instrumentation
  • Surveillance
  • Excavation

Where we operate

We offer our services worldwide. Equipment is largely containerized, ready for global shipping.

Contact

Contact person

Anne-Lise Berggren, Ph.D., M.Sc
Senior geotechnical specialist
 (+47) 95 29 29 30
 Anne-Lise.Berggren@geofrost.no

Enquiry

With brief overall project info, we quickly provide rates and price estimates on request.

Clients