Abstract: Researching the freeze-thaw cycle, freezing temperature and freezing rate is of vital significance for engineering prevention of freezing-thawing hazard of loess. In this paper, the changes in unconfined compressive strength, shear strength, and compressibility of loess samples after a single freezing-thawing cycle at different freezing temperatures were studied. Samples of different moisture contents were frozen at 0, -5, -10, -15, -20 ℃ in a closed environment, respectively, and then heated at 15 ℃. Results showed that after freezing and thawing at different freezing temperatures, the unconfined compressive strength of loess with different water content decreased; and the lower the freezing temperature, the faster the unconfined compressive strength decreased. The cohesion of soil samples with different moisture contents also exhibited a tendency of decreasing with the drawdown of freezing temperature. The friction angle of loess decreased firstly and then increased within a range between 0° and 2°. For loess with 14% and 26% moisture content, the increment in compression coefficient was larger than 0.1 MPa^-1 under -20 ℃ freezing temperature, while under other low temperature conditions, the changes in compression coefficient were slight; whereas loess of 18% and 22% moisture content showed a more uniform fluctuation with the decrease of freezing temperature, with the fluctuation value in the case of adjacent negative temperature did not exceeding ±0.1 MPa^-1.

Key words: loess, freezing temperature, moisture content, unconfined compressive strength, compression factor