Literature Review on Building Envelope, Heating and ... - Beeshive.org

• Soil characteristics: Frozen soil provides excellent bearing for a structure. When
soil, usually fine-grained, thaws, it turns into slurry with little strength. This can lead
to large movement, and the structure might fail.
Foundations
Johnston (1965) presented four approaches for foundation design in a permafrost
environment. The results of site investigation will indicate the design approach and the
construction technique to be used.
• Conventional design and construction methods - I: Permafrost conditions can be
neglected when the site is well-drained granular soils or solid rock, because they
contain little or no ice.
• Conventional design and construction methods – II: If it is not possible to preserve
the frozen conditions, two approaches are possible: in areas where ground
temperatures are close to 0ºC (32ºF), thaw and then consolidate the soil prior to
construction, or remove the soil and replace it with compacted, well drained, nonfrost-susceptible
material.
• Pile foundations: Pile foundations in drilled holes to 4.6 to 9 m (15 to 30 ft.) depth
could be used when the permafrost conditions can be preserved and thus could be
used to support a structure. Ventilation or insulation can be used to preserve
permafrost. Ventilation is commonly used with heated buildings. The structure is
raised above the ground surface to permit air circulation beneath to minimize or
prevent heat flow to the ground.
• Flexible foundations: In areas with anticipated settlement, flexible foundations can
be used, which can be adjusted to eliminate structural deformation as differential
settlement occurs. To ensure stability of the structure, special settlement joints could
be incorporated, which permit individual sections of the building to move without
causing deformations in adjacent sections.
Screw Piles Foundation, Permafrost, Alaska
Johnston et al. (1999) discussed the versatility and effectiveness of screw piling for
building foundations in soils with inadequate bearing capacities for conventional concrete
footings. Screw pile foundations are effective for supporting construction on low-bearing
capacity materials, such as the peat and saturated marine silt deposit soil in Juneau,
Alaska, that has inadequate bearing capacities.
The screw piling foundation method involves the use of a power head and pile driver to
penetrate the permafrost active layer and insert bearings in the inactive layer. The screw
piles consist of a plate or plates, formed into the shape of a helix or screw thread attached
to a central shaft. Advantages of the screw piling method include the absence of impact
and vibrations that may be harmful to adjacent buildings, as compared to driving wood or
steel piles into the soil. Screw pilings are also quickly and easily installed at a lower cost
than traditional methods.
PERD-079: Task 2 - <strong>Literature</strong> <strong>Review</strong> 36