Landslides and Moisture-Temperature for Cutting Slope Soil in Freeze-Thaw Cycles

摘要

It is the main problem for highway in seasonal frozen regions that soil cutting slope instability causing by freeze-thaw, which affected traffic safety and the environment seriously. Relying on the silty clay slope, which is in the Tong-San highway expansion project from Jiamusi to Harbin, using triaxial shear tests, field monitoring, the mechanism of slope instability causing by freeze-thaw was studied. Triaxial test results show that: when the soil water content is less than the optimum water content, the soil cohesion is increased with the increase of moisture. The soil cohesion is decreased with the increase of moisture, when the soil water content is bigger than the optimum water content. The peak value of soil cohesion is near the optimum water content. The internal friction angle of soil is decreased with the increase of moisture. Soil cohesion is decreased with the increase of times of freeze-thaw cycles. Field monitoring results indicates that, during the process of soil freezing, moisture migrates to the freezing-front. In the melting period of spring, because of the accumulating water within the cracks of temperature shrinkage, and longer duration of zero temperature below the slope surface, the melting water was hampered, as well as the water frozen within the soil body melt rapidly when soil body temperature reaches 0.1 °C, all of these results in the water content in shallow slope is too high, and soil shear strength decreases, then occurs cutting slope landslides.