Abstract
Frost heaving of slowly thawing welded tuff has reported so far. However no report is seen on frost heaving in thawing frozen soils. In this paper frost heaving in thawing process of variety of frozen soils such as frozen clay, silt and fines containing sand are demonstrated and discussed the mechanism. A main point of the discussions is the role of the tensile strength developed in frozen fringe. The tensile strength of the frozen soil in the frozen fringe temperature range is reported as some hundreds kPa.When the ice pressure given by the Generalized Clausius-Clapeyron Equation overcomes the tensile strength an isotherm in frozen fringe, the frozen soil splits at the isotherm. This event leads the depression of unfrozen water pressure and super cooling at the plain of the splitting. These two conditions are thought to be the resources of frost heaving observed in thawing frozen soils.
