GEOPHYSICS IN THE DEFINITION OF THE GEOLOGY OF A SITE IN SOUTHEAST ALASKA AND THE APPLICATION OF DATA TO THE DESIGN OF AN EMBANKMENT

A tailings impoundment is being designed for a new underground mine on Admiralty Island, Alaska. The tailings impoundment embankment will be constructed across a valley containing deep deposits of glacially derived sediments. This paper describes geophysical exploration which was carried out at the site to define bedrock quality and topography and to characterize the sediments filling the bedrock valley. The geophysical work included seismic refraction and electrical resistivity surveying which was used to plan other geotechnical explorations including drilling boreholes, undisturbed soil sampling and in-situ testing with an in-situ pressuremeter and a piezo cone. The seismic lines were used to construct maps showing bedrock topography. The seismic lines indicated the shape of the bedrock surface and rock quality to be highly variable. The resistivity data interpreted in the light of the other geotechnical exploration work showed that the bedrock valleys are filled with sequences of gravel, boulders, sand, silt and silty clay. The geophysical survey was most useful in defining the complex bedrock topography and providing information concerning the general character of the overburden. The seismic and electrical resistivity results were used to optimize the locations of a few test borings at the most critical locations thereby minimizing the expense of site selection and design studies.

• Supplemental Notes:
  • This paper was presented at the Twentieth Annual Engineering Geology & Soils Engineering Symposium, Boise, Idaho April 7&8, 1983.
• Corporate Authors:

  Idaho Department of Highways

  P.O. Box 7129
  Boise, ID  United States  83707
• Authors:
  • Schwarz, S D
  • Cadwell, J A
  • Wilke, S
  • Ringstad, C A
  • Chedsey Jr, G L
• Publication Date: 1983

Media Info

• Pagination: p. 1-18
• Serial:
  • Engineering Geology & Soils Engineering Symp Proc
  • Publisher: Idaho Department of Highways

Subject/Index Terms

• TRT Terms: Bedrock; Design; Embankments; Geology; Geophysical prospecting; Mapping; Refraction; Resistivity method; Seismicity; Surveying; Topography
• Uncontrolled Terms: Seismic refraction
• Old TRIS Terms: Geophysical explorations
• Subject Areas: Design; Geotechnology; Highways; I41: General Soil Surveys;

Filing Info

• Accession Number: 00380605
• Record Type: Publication
• Files: TRIS, STATEDOT
• Created Date: Mar 30 1984 12:00AM