The Need for Geotechnical Investigationby Edwin S. Clarke, P.E., (F.ASCE),
Knowledge of the subsurface conditions is needed to decide which type of foundation to use. In the discontinuous permafrost zone, some generalizations may be made about the location of permafrost. These should be considered unreliable. Experience has shown that the boundaries of frozen and non-frozen soil are very irregular. Even the presence of existing spread footing foundation may not be proof positive that the ground is stable, as there may be frozen ground under the building with excessive moisture that has not yet thawed. The soil type, thermal state, and amount of potential settlement determined by the geotechnical investigation will guide the designer in selecting a foundation type. The techniques presented below are those used by the author's firm. Other firms may use more conservative approaches.
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