Slope Instability Phenomenon in the Permafrost Region Along the Qinghai–Tibetan Highway, China

Abstract

The area of permafrost occupies 150 × 10⁴ km² on the Tibetan Plateau. Slope stability in permafrost regions is one of serous geological problems in the construction of the Qinghai–Tibetan Highway, which has been claimed to be an environment harmony project. Based on the field investigation, it is found that the main types of slope failure in the permafrost regions include slope collapse, slope creeping, surface vegetation creeping, debris flow and thaw-slumping. Among which, the thaw-slumping is the most hazardous one to the environment, vegetation and the engineering. The slumping may attribute to engineering excavation, which can disturb the thermal balance of the slope soil and cause thawing. As the slope soil thawing, the strength decreases in a large extent or even lost mostly, then the slope may fail in a very low slope angle. The countermeasures for the thermal thawing slides should maintain the frozen state of the soil for keeping from thawing, using methods such as covering with coarse material which can prevent heat absorption and be good for heat release.