Application of the calculating scheme for rock freezing depth during geotechnical monitoring on the Anzob pass (Tajikistan)

Abstract

Rock instability in high-altitude areas is an important risk factor for humans and infrastructure, especially in the context of climate change. The presence of water in the rock leads to a clear increase in the strength of the rock, the effect is enhanced at lower temperatures and a higher degree of saturation. Since the decrease in rock strength due to the phase transition from frozen to thawed state has a great impact on the strength and stability of the rock soil, the paper proposes a model and a numerical method for estimating the depth of rock soil freezing based on data on air temperature and the thickness of the snow cover. The paper also evaluates the effect of air temperature and snow cover on the rock soil stability and depth of freezing according to the proposed calculation algorithm which is applied for the winter periods 2010/2011-2019/2020 at the Anzob pass in Tajikistan. The calculating scheme is constructed according to the three-layer medium thermal conductivity problem (snow, frozen and thawed rock) with a phase transition on the boundary frozen and thawed rock soil. The equation of heat balance contains the heat of the phase transition, the energy of inflow from the thawed rock and the outflow into the frozen rock and, in the presence of snow cover, the outflow into the atmosphere air through it.