construction methods in permafrost
Link: http://w3id.org/permafrost/v/ipaglossary/t0043
Within: IPA Permafrost Glossary
Definition: Special design and construction procedures required when engineering works are undertaken in permafrost areas.
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construction methods in permafrost
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Design and construction of engineering works on permafrost normally follow one of two broad principles which are based on whether or not the frozen foundation soil or rock is thaw-stable (thaw-stable permafrost) or thaw-unstable (thaw-sensitive permafrost). Permafrost conditions can be neglected, and conventional designs and construction methods used when foundation materials are stable upon thawing. When the foundation materials are thaw-sensitive, however, then either the "passive" or "active" design and construction method is selected. The passive method maintains the foundation materials in a frozen state. Preservation of the frozen condition or permafrost aggradation can be accomplished using thermal piles or thermosyphons, or by using either a ventilation or an insulation construction technique; often a combination of these techniques is used. The ventilation technique requires that there is a clear space left between the bottom of the structure and the ground surface, or that the structure is placed on a fill pad with ducts incorporated in the pad or the floor system. Movement of cold air through the air space or ducts dissipates heat from the structure above and removes heat from the ground below. Using the insulation technique, a relatively thick fill (sometimes containing a layer of insulation) is placed on the ground surface to prevent thawing or to reduce or control the depth of thaw below the original ground surface. When permafrost degradation cannot be prevented, then one of the active methods must be considered. Two main approaches are possible. Unfavourable foundation materials are thawed and compacted or replaced with more suitable materials before the structure is erected. Alternatively, the foundations and structure are designed to accommodate the thaw settlements that will occur.
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https://doi.org/10.4224/20386561
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