Abstract: To study the strength deterioration rules of saturated sandstone under freeze-thaw cycles, laboratory freeze-thaw tests were carried out on two groups of sandstone with different initial porosities under water saturation. On the basis of measuring the porosity variation, static peak strength and dynamic peak strength, the evolution law of porosity variation and loss rate of peak strength were analyzed within the whole freeze-thaw cycles. The extent of freeze-thaw damage was compared between the two groups sandstone by using the porosity variation to measure freeze-thaw damage. A relative residual peak strength deterioration model of saturated sandstone under freeze-thaw cycles was established based on the porosity variation. The same function as the strength deterioration model of saturated sandstone was selected to fit the test data，showing a good correlation. Within the whole freeze-thaw cycles, the porosity variation and loss rate of peak strength increased with the freeze-thaw cycles for two groups of sandstone. Freeze-thaw damage of group B was higher than that of group A, but its loss rate of peak strength was lower than group A, which indicates that the peak strength of saturated sandstone is affected by freeze-thaw cycles and strain rate and this two factors have completely opposite effect mechanism. There exists a good fitting relationship between the relative residual peak strength and the porosity variation of saturated sandstone under freeze-thaw cycles, which shows that the porosity variation before and after freezing-thawing is suitable for evaluating the relative residual peak strength of saturated sandstone after freeze-thaw cycles.

Key words: freeze-thaw cycles, freeze-thaw damage, strength deterioration model, porosity, strain rate