Basic Study on the Frost Heave Pressure of Rocks: Dependence of the Location of Frost Heave on the Strength of the Rock

Frost heave in rocks is caused by the frost heave pressure (pore ice pressure) generated by the freezing of pore water, which then cracks the rock. This work attempts to clarify the frost heave pressure of rocks by experiments at four temperature conditions. Ohya tuff and Kimachi sandstone, in which the occurrence of frost heave has previously been confirmed, were used as specimens. Measurements of these experiments were the internal temperature of the rocks during the freezing process and the location where the ice lens formed. These two parameters made it possible to determine the temperature of the location where the ice lens formed. A generalized Clausius-Clapeyron equation was used to calculate the pore ice pressure. The results indicated that the temperature at the location of the ice lens formation depends on the types of rock, but not on the temperature gradient during freezing. It was also confirmed that frost heave in rocks with a higher tensile strength appears at locations with a lower temperature, while that in rocks with a lower tensile strength appears at location of temperatures close to 0°C. These findings suggest that the location and temperature of the ice lens formation are dependent on the strength of the rock.