Search

Traditionally, frost heave of foundations has been avoided by placing the foundations below frost penetration depth. An alternate and, under certain conditions, a more economical method is to place the foundation on or near the ground surface, and isolate the surrounding and underlying soil from seasonal frost activity. Such an approach reduces the cost of excavation and backfill, and reduces the volume of concrete needed for normal foundations. A method is presented for determining the thickness and width of insulation needed. The insulation is placed beneath and around the foundations, as required. The design guides may be used for both heated and unheated structures. The method is based on a theoretical and practical study carried out by the writers on actual insulated foundations used for industrial buildings near Timmins, Ontario, Canada.

Preliminary tests in the new large-scale testing facility at the University of Toronto reveal that bearing capacity on a pile volume basis is more efficiently developed by a long slender pile or a group of short slender piles than by a pile of larger diameter. The authors attribute this to increased arching in the soil around the pile of greater volume displacement, believing arching buffers the pile from the effects of lateral soil pressure.