Construction pits

Waterproof construction pit support in any ground condition.

Contracting services

Construction pit

Figure: Construction pit with Geofrost walls.

Geofrost delivers temporary support for construction pits for various depths with flexible shapes. The walls can go down to rock or float.

The Geofrost walls become waterproof regardless of ground condition and can enclose pipes and cables. The construction pit becomes waterproof if the walls reach down to an impermeable layer, to a waterproof frozen bottom or to another constructed waterproof bottom. This provides excellent groundwater control and an 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 walls are usually established without stiffeners or tie backs, enabling continuous and efficient excavation.

Construction pit bottom

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

Geofrost offers waterproof temporary construction pit bottom with flexible shape, attaching to existing walls and constructions with good adhesion to other materials. The bottom is made so thick that the weight balances the water pressure.

Foto: Geofrost construction pit bottom.
The bottom is constructed from above groundwater level, so the pit is waterproof when excavation starts. If the bottom needs maintenance freezing during the construction period, the pipes are reconnected after excavation.

Waterproof bottom is applicable when water ingress through the bottom becomes problematic. Typical problems are flooding risk, stability issues or pore pressure reduction in the surroundings and associated risk for settlements.

Retaining wall

Figure: Cantilever Geofrost wall fixed in bedrock.

Photo: Insulation of Geofrost wall.
Geofrost delivers temporary stable cut slopes and waterproof retaining walls.

The Geofrost wall is particularly suitable in coarse soils, since it is easier to drill single holes through for example moraine or talus containing boulder, than to ram sheet piles. Also in extra challenging ground, such as man made ground and old quay structures, it is easier to get through with single holes than with a continous construction. The ground freezing ensures continuity of the wall between the single holes.

Photo: Geofrost walls crossing tram tracks in use.
Cables and wires are often rerouted temporarily in own contracts for preparatory work, because they cross the path of the retaining wall. Geofrost walls can be made continously across tracks, cables and pipelines which will be in operation in the construction period, so extra diversion is avoided.

Underpinning

Figur: Frost som midlertidig understøttelse av hus.

Geofrost delivers temporary underpinning of foundations in connection with deeper excavation adjacent to or below the construction needing support.

Photo: Frostvegg under fundament.
Freezing pipes are drilled next to the construction so the frost can spread in under and ensure good vertical load transfer without any intervention in the construction to be underpinned.

If the foundations are to be extended further down from existing level, the frozen soil is made wide enough to enable sectionwise excavation right under the foundation and construction of extensions or new foundations.

Soil anchor

Geofrost delivers temporary soil anchors with large surface area with full friction toward surronding soil and thereby high capacity.

The anchors can be made in any ground condition, but get highest capacity below ground water level. The anchors can be combined with different kinds of retaining walls and kept active as long as the wall has a function.

Ground improvement

Figur: Grunnforsterkning ved grunnfrysing,

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

Photo: Pelemaskin på frostforsterket underlag.
Geofrost ground improvement may also be used for temporary access across vulnerable land that needs protection against mechanical wear. The frozen soil thaws after use.

Waterproofing

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

Geofrost delivers waterproofing and groundwater curtains as supplement to other constructions for groundwater control, such as transition between sheet pile and rock and groundwater curtains further down in weathered rock and coarse soils. We also provide waterproofing of leaking sections in sheet piles, secant piles and jet grout piles.

Ground freezing has good adhesion to other construction materials and can therefore be combined with steel, wood or concrete. The frozen soil completely seals toward any material and irregularities. Ground freezing is the most reliable method for sealing and groundwater control.

Cofferdam

Figure: Geofrost wall through rock fill.

Geofrost provides impermeable core in rock fill to be used as cofferdam for construction works in areas normally covered by water.

The rock fill can be dumped directly on the bottom without replacement of soft and permeable soils. Drilling is easily carried out through the fill further down through the permeable layer and weathered rock such that a completely waterproof cofferdam is obtained.

Benefits

Any ground condition

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, landfills and rocks of various quality. This makes freezing work equally well for transition zones between soil and rock and for soil containing block and 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.
  • The earth support is installed from above groundwater level and is compeletly waterproof at start of excavation.

Efficient excavation to significant depth

The Geofrost wall's capacity is increased by increasing thickness, enabling great depths without stiffeners or anchors. The construction pit walls are ready when excavation starts, enabling continuous excavation and reduced construction time.

Free geometry

The freezing pipes are freely positioned, with any inclination, so the earth support gets the desired shape; as long as you can drill, you can freeze. Although the freezing pipes are placed individually, a continuous 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.

Low CO2 footprint

Ground freezing has generally a low CO2 footprint. If Geofrost earth support is used in a project in Norway for one year, the CO2 footprint will be reduced by 80 % compared to a sheet pile wall of the type AZ-48 or equivalent.

What we deliver

We are a total supplier of retaining walls and impermeable construction pits by ground freezing and offer all related services within consulting and contracting.

We deliver designed and engineered construction pits, ready for access and installation, or a limited scope adapted to project and client.

Consulting services

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

Contracting services

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

Where we operate

We offer our services worldwide.

Contact

Contact person

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

Enquiry

If you have questions or would like more information, please contact us. With project info, we quickly provide price estimates.

Ground freezing services since 1986.

Clients