FOUNDATIONS ON SWELLING AND SHRINKING CLAYS

Many natural and man-made deposits of soils which contain substantial proportions of clay mineral particles have potentials for swelling or shrinking with change in water content. The degree to which these potentials are developed and the rate with which volume changes take place are governed by the environmental changes to which these soils are subjected. The magnitude and direction of volume change will depend on many factors, including the mineralogy of the clay minerals present, the relative proportion of active clay-size particles to non-clay particles, the initial moisture, density, particle structure and stress conditions of the soil, the new environmental conditions imposed on the soil, and the time available for response by the clay. Traditional foundations for light structures on these clays usually have very large safety factors with respect to bearing capacity or settlement but often give poor service because they transmit large distortions to the superstructure. These distortions arise from sizeable volume changes in soils below or around the structure caused by external forces of climate and vegetation or reactions by the soils to changed effective stresses and temperatures due to the influence of the structures. In soils of medium to high potential volume change, the foundation design will likely be governed by the need to limit distortions caused by these types of reactions rather than by classical shearing strength-bearing capacity or consolidation-settlement limitations.

  • Supplemental Notes:
    • This article is an excerpt from the Proceedings of the Fourteenth Annual Engineering Geology and Soils Engineering Symposium that was sponsored by Idaho Transportation Department, Division of Highways; University of Idaho, Department of Geology and Department of Civil Engineering; Idaho State University, Department of Geology and Department of Engineering; and Boise State University, Department of Geology, and Department of Physical Science and Engineering. This symposium was held at the Rodeway Inn, Boise, Idaho, and was hosted by Boise State University.
  • Corporate Authors:

    Idaho Department of Highways

    P.O Box 7129
    Boise, ID  USA  83707
  • Authors:
    • Hamilton, J J
  • Publication Date: 1976-4-9

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Filing Info

  • Accession Number: 00142677
  • Record Type: Publication
  • Files: TRIS, STATEDOT
  • Created Date: Feb 1 1977 12:00AM