Determination of Thermal Conductivity and Volumetric Heat Capacity of Soils Near the Surface

Abstract Thermal conductivity and volumetric heat capacity of a soil near its surface are in situ simultaneously determined using a heat flux plate on the soil surface and thermocouples in the soil. The rise of the temperature caused by a heat pulse of short duration is recorded. The time involved in numerical calculations is greatly reduced by the use of Laplace transforms of heat flux density and rise of temperature. The heat flux into the soil under natural conditions can be calculated from the temperature recorded in the absence of the heat flux plate using the thermal conductivity as it has been determined. The method is applied to a sand soil and to a peat mulch on sand, which were at uniform initial temperature. Theory is emphasized. A discussion of some experimental problems, met in in situ determinations, will be given in a subsequent paper.