CONSOLIDATION OF FINE GRAINED COLUMBIA RIVER ALLUVIUM

The settlement of structures built on normally consolidated, fine grained alluvium is a common engineering consideration. Total settlement results from a combination of initial elastic settlement, primary consolidation, and secondary compression. The reliability of predictions for total settlement is affected by how well these components are recognized and understood. Conventional laboratory tests are used to evaluate primary consolidation. Methods which reliably predict secondary settlement on the basis of laboratory data are not well established in engineering practice. Preloading a site is a method to improve subsurface conditions and reduce the magnitude of final settlement beneath a structure. A preload fill is placed to preconsolidate or overconsolidate the site prior to construction, so that settlements occurring after construction are tolerable. During the course of developing an industrial site along the lower Columbia River, a preload was used. This paper describes the site conditions, summarizes the extensive laboratory testing on samples obtained from the site, and presents the results of field settlement measurements during the preloading. The field measurements indicate that secondary settlement is a nt portion of the settlement experienced on the soft sand silts and clayey silts which comprise the lower Columbia River aluvium. It is shown that conventional laboratory consolidation tests can be used to reasonably predict secondary compression settlement. Index properties were statistically correlated with primary consolidation parameters. It is proposed that these correlations are usable for purposes of preliminary analyses on future projects at sites with similar geologic history.

  • 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  United States  83707
  • Authors:
    • Rippe, A H
    • Schroeder, W L
  • Publication Date: 1976-4-9

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Filing Info

  • Accession Number: 00142681
  • Record Type: Publication
  • Files: TRIS, STATEDOT
  • Created Date: Feb 1 1977 12:00AM