THE PERFORMANCE OF A FROST-TUBE FOR THE DETERMINATION OF SOIL FREEZING AND THAWING DEPTHS

INSTRUMENTAL METHODS FOR DETERMINING THE POSITION OF THE FROST LINE HAVE SEVERAL DRAWBACKS: THE RELATIVELY HIGH INITIAL EQUIPMENT COST FOR INSTRUMENTS, SENSORS, AND CALIBRATION; EXPENSIVE AND TIME-CONSUMING MEASUREMENTS, OFTEN UNDER SEVERE FIELD CONDITIONS; AND GENERATION OF DATA THAT DO NOT ALWAYS INDICATE THE PRECISE POSITION OF THE FROST LINE, AS THE LATTER DEPENDS ON PARTICLE SIZE AND MOISTURE CONTENT. PHYSICAL PROBES ARE THE MOST SIMPLE AND DIRECT METHOD OF OBTAINING THAW DATA IN WET SOILS, IN LOW- MOISTURE MATERIAL, AND IN GRAVELLY SUBSTRATA. THE PRESENT ARTICLE REPORTS THE RESULTS OF LABORATORY AND FIELD TESTS WITH A SIMPLE DEVICE THAT ACCURATELY DETERMINES THE DEPTH OF ZERO-DEGREE ISOTHERMS IN FREEZING AND THAWING SOILS. ITS REPRODUCIBLE READINGS COMPARE FAVORABLY WITH MORE SOPHISTICATED METHODS OF MEASUREMENT, IT CAN BE READ EASILY BY NONTECHNICAL OBSERVERS WITHOUT AUXILIARY INSTRUMENTS, IT CAN BE FABRICATED IN THE FIELD, AND ITS COST IS RELATIVELY LOW. THE DEVICE CONSISTS OF AN OUTER POLYETHYLENE TUBE PERMANENTLY INSTALLED IN THE SOIL AND AN INNER, REMOVABLE TUBE CONTAINING A FLUORESCEIN-SATURATED SAND MIXTURE. A COLOR CHANGE FROM GREEN TO PALE YELLOW OCCURS IN THE DYE UPON FREEZING; THAWING RESULTS IN REAPPEARANCE OF THE GREEN COLOR. COLOR CHANGES IN THE TUBES CORRESPOND CLOSELY TO PHASE CHANGES IN THE PORE WATER OF ADJACENT SOILS AT SIMILAR DEPTHS. THE INSTRUMENT, A MODIFICATION OF A SWEDISH AND CANADIAN DESIGN, WAS FIELD-TESTED IN ALASKA IN 1968 AND 1969. THE ARTICLE COVERS A PRELIMINARY LITERATURE SURVEY, CONSTRUCTION OF THE TUBE, LABORATORY EVALUATION, AND FIELD EVALUATION. FIVE POTENTIAL USES OF THE DEVICE ARE LISTED.

  • Authors:
    • Rickard, W
    • Brown, J
  • Publication Date: 1972-2

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 149-54
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00238045
  • Record Type: Publication
  • Files: TRIS
  • Created Date: May 1 1972 12:00AM