Tensile strength and stress–strain behaviour of Devon silt under frozen fringe conditions

Frost heave is attributed to the segregation of ice and ice lens formation as a soil freezes. Ice lens formation and hence frost heave starts with the cracking of the frozen fringe. In order for these cracks to initiate and open, the tensile strength of the soil has to be exceeded. Therefore, any evaluation of the ice lens initiation condition requires the determination of the tensile strength in the frozen fringe. Four point bending tests were carried out to determine the tensile strength of the frozen fringe and its stress-strain behaviour. Devon Silt samples frozen over a range of frozen fringe temperatures (0 to − 1.5 °C) were tested at different deformation rates (0.08 mm/min to 8.0 mm/min). The frozen fringe of Devon silt has considerable tensile strength. The results show the dependency of the tensile strength on the temperature, the deformation rate, and the unfrozen water content. A unique strain rate dependency was determined for the frozen fringe. Further, it was observed that the stress-strain behaviour is influenced by the deformation rate and the subzero temperatures.

Research highlights
► Cracks in the frozen-fringe play a great role in the frost heave process.
► Tensile strength of soils has to be exceeded for the cracks to form.
► Tensile strength and stress-strain behaviour of the frozen fringe is examined.
► Devon silt possesses considerable tensile strength under frozen fringe condition.
► Stress-strain behaviour is influenced by deformation rate and subzero temperature.