Format:
v, 45 Seiten
,
Illustrationen
Series Statement:
Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 324
Content:
CONTENTS: Preface. - Introduction. - Resistivities of earth materials. - Dependence of resistivity on soil type. - Relation between resistivity and water content. - Dependence of resistivity on temperature. - Dependence of resistivity on ice content. - Resistivity of rocks. - Theory and method. - The E-phase system. - Calibration. - Analogue recorder. - Magnetic recorder. - Flight path recovery camera. - Altimeter. - Data reduction. - Horizontal control. - Computation of apparent resistivity. - Computer processing of data. - Plotting and contouring of data. - Filtering of E-phase data. - Problem areas of the E-phase technique. - Horizontal control. - Zero error. - Interference. - Ground control in study areas. - Computer modeling of resistivity profiles in central Alaska. - Results. - Goldstream site. - Site 2. - Chena Hot Springs Road. - Moose Creek Dam. - Conclusions. - Literature cited. - Abstract.
Content:
Airborne resistivity methods using radio waves in three frequency bands were tested in the vicinity of Fairbanks, Alaska. The test sites were selected because much ground control is available for this area. The objectives of this study were to determine the ability of these methods to map permafrost and other soils and to investigate the advantages of multifrequency mapping. Investigations in permafrost regions for such geotechnical endeavors as route selection for roads and pipelines and site investigation for building and dam construction often require that a careful assessment be made of the presence or absence of frozen ground, of the ice content of frozen ground, and of the depth of frozen ground. The airborne resistivity data obtained in this study were contoured and the contour maps were compared with surficial geological maps and other ground truth data available. The following conclusions were reached: 1) in areas where the near surface sediments are relatively uniform; VLF resistivity best delineates permafrost; and 2) in areas where surface sediments vary widely (e.g., recent flood plains), resistivity at all frequencies gives little information on permafrost conditions, but provides other important information, such as bedrock type, depth to bedrock, soil type and layering.
Note:
MAB0014.001: ZSP-202-324
,
Online frei verfügbar
In:
Research report
Keywords:
Forschungsbericht
URL:
http://www.worldcat.org/oclc/832023836
