Principles of construction on permafrost (bases and foundations)

For construction outside the permafrost regions it is usually believed that all the load from a structure is transmitted through the base of the foundation to bearing ground while ground in contact with the sides of a foundation only occasionally carries a vertical load (as with piles and deep foundations). The interaction between foundations and ground is assessed differently in the regions of deep seasonal freezing and of permafrost. The load is transmitted to ground here through all the ground surfaces in contact with the foundation. This is associated with the fact that adfreezing of the foundation surface to the ground occurs with the result that tangential and normal stresses are transmitted from the ground to the foundation and from the foundation to the ground. The value of the transmitted stresses is then limited by the strength of adfreezing.

The direction of the stresses arising in the interaction between a foundation and the ground can change with time and depends upon the layer (seasonally or perennially freezing) in which the foundation is situated. The main types of embedding of foundations are shown in Fig. 18.1. Thus, within the layer of seasonal freezing (or thawing), tangential stresses transmitted from ground to the foundation develop during the part of a year in which the layer freezes and heaves, and are directed upwards .