Thawing Frozen Ground: Field Trials and Analysis

Abstract

Field trials and analytical modeling are conducted in order to evaluate methods for thawing frozen ground. Propane heaters, electric heaters, and coal and straw fires are built over specially constructed test pads. Surface and ground temperatures are monitored in order to compare the different methods. Two soil types are considered: a sandy gravel and a clay till. Following field testing, an analytical model is developed based on the measured fire temperatures, and is used to predict the soil response with time. Comparisons of the field data and model predictions are presented. The data gathered indicated that the three techniques tested are capable of thawing frozen ground. After 96 hrs, the depth of thaw in clay soils ranges from 0.9 m to 1.25 m, and up to 1.5 m after 96 hrs in gravel soils. The time for the heat to penetrate about 0.3 m of soil is found to range from 2 to 8 hrs.