Influence of air temperature change on stability of permafrost slope: A case study of shallow permafrost landslide in Qinghai Province

Abstract

Under the influence of air temperature change, shallow permafrost landslide is a complex thermal-hydro-mechanical coupling process, which involves the transformation of water between solid state and liquid state. To reveal the influence of air temperature change on the shallow permafrost landslide, based on the coupled thermal-hydro-mechanical model for frozen soil, the thermal-hydro-mechanical evolution process of slope in permafrost region from 2020 to 2024 is simulated. The results are as follows: the rate of water migration presents periodic variation. The thawing degree of the active layer from May to October is high, causing the variation trend of total water content significantly. In summer, the thawing of the high ice content layer below the permafrost table forms a water-rich layer of 15 cm thickness approximately, causing excess pore water pressure difficult to dissipate. The permafrost table will decline by 10.4 cm in 4 years, and the thickness of the active layer and water-rich layer increased. As a result, the sliding force of the overlying thawed soil increases, the sliding resistance decreases, and the shear strength of the soil further decreases. Several centimeters displacement of frost heave and thaw settlement occurs in the active layer per year, shear strength deteriorates continuously, and the weak zone is easiest formed at slope toe.

Keywords

• active layer
• coupling of seepage-temperature-stress
• permafrost degradation
• water migration
• frost heave and thaw settlement
• shallow permafrost landslide