Abstract: EQUIPMENT AND METHODS OF TEST TO DETERMINE THE COEFFICIENT OF THERMAL CONDUCTIVITY OF SOILS AT VARIOUS CONDITIONS OF MISTURE CONTENT AND DENSITY ARE DESCRIBED. TESTS WERE MADE ON NINETEEN DIFFERENT SOILS WHICH REQRESENTED A WIDE TEXTURAL VARIETY, GRAVEL, SAND, SANDY LOAM, SILT LOAM, AND CLAY, AS WELL AS SOME CRUSHED ROCKS AND A FIBROUS PEAT. MOISTURE CONTENTS FOR TESTS VARIED FROM AIR-DRY TO VALUES GREATER THAN THE OPTIMUM MOISTURE CONTENT; DENSITIES VARIED FROM A LOOSELY-POURED CONDITION TO THE MAXIMUM OBTAINABLE BY HEAVY RAMMING. SOILS WERE TESTED AT SEVERAL MEAN TEMPERATURES. THE MOST IMPORTANT INFLUENCE OF TEMPERATURE DEPENDS ON WHETHER IT IS ABOVE OR BELOW FREEZING. FOR MOISTURE CONTENT INCREASES ABOVE ABOUT 6 TO 12 PERCENT, THE CONDUCTIVITY OF FROZEN SOILS BECOMES PROGRESSIVELY GREATER THAN THAT OF THE UNFROZEN SOIL. DENSITY AFFECTS THE THERMAL CONDUCTIVITY OF A SOIL IN ABOUT THE SAME MANNER FOR ALL SOILS, AT ANY MOISTURE CONTENT, AND FOR EITHER THE FROZEN OR UNFROZEN CONDITION. ON THE AVERAGE EACH ONE-POUND PER CUBIC CUBIC FOOT INCREASE IN DENSITY INCREASES THE THERMAL CONDUCTIVITY BY ABOUT 3 PERCENT. AN INCREASE IN MOISTURE CONTENT CAUSES AN INCREASE IN THERMAL CONDUCTIVITY. THIS IS TRUE UP TO THE POINT OF SATURATION. THE THERMAL CONDUCTIVITY OF A SOIL, AT A GIVEN DENSITY AND MOISTURE CONTENT, VARIES IN GENERAL WITH THE TEXTURE OF A SOIL, BEING RELATIVELY HIGH FOR COARSE TEXTURED SOILS AND RELATIVELY LOW FOR FINE TEXTURED SOILS. THE MINERAL COMPOSITION OF THE SOILS ALSO EFFECTS THE CONDUCTIVITY. QUARTZ TENDS TO GIVE HIGH VALUES WHEREAS MINERALS SUCH AS PLAGIOCLASE FELDSPAR AND PYROXENE, WHICH ARE CONSTITUENTS OF BASIC ROCKS, TEND TO GIVE LOW VALUES OF THERMAL CONDUCTIVITY. FOUR CHARTS ARE PRESENTED TO AID IN THE ESTIMATE OF THE THERMAL CONDUCTIVITY OF A SOIL. TWO OF THE CHARTS ARE FOR SANDS OR SANDY SOILS, AND TWO FOR SILT AND CLAY SOILS. ONE OF THE CHARTS FOR EACH TYPE OF SOIL IS FOR THE FROZEN CONDITION, THE OTHER FOR THE UNFROZEN. THESE CHARTS WILL GIVE CONDUCTIVITY VALES WITHIN AN ACCURACY OF 25 PERCENT. /AUTHOR/
Publication Year: 1949
Publication Date: 1949-01-01
Language: en
Type: article
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Cited By Count: 54
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