Alpine permafrost environments are highly vulnerable and sensitive to changes in regional and global climate trends. Thawing and degradation of permafrost has numerous adverse environmental, economic, and societal impacts. Mathematical modeling and numerical simulations provide powerful tools for predicting the degree of degradation and evolution of subsurface permafrost as a result of global warming. A particularly significant characteristic of alpine environments is the high variability in their surface geometry which drives large lateral thermal and fluid fluxes along topographic gradients. The combination of these topography-driven fluxes and unsaturated ground makes alpine systems markedly different from Arctic permafrost environments and general geotechnical ground freezing applications, and therefore, alpine permafrost demands its own specialized modeling approaches. In this work, we present a multi-physics permafrost model tailored to subsurface processes of alpine regions. In particular, we resolve the ice-water phase transitions, unsaturated conditions, and capillary actions, and account for the impact of the evolving pore space through freezing and thawing processes. Moreover, the approach is multi-dimensional, and therefore, inherently resolves the topography-driven horizontal fluxes. Through numerical case studies based on the elevation profiles of the Zugspitze (DE) and the Matterhorn (CH), we show the strong influence of lateral fluxes in 2D on active layer dynamics and the distribution of permafrost.

In the global warming trend, the permafrost area is decreasing. And the change of temperature seriously affects the safety and stability on Open-pit slope under the alternation of freezing and thawing. Based on FLAC(3D), the simplified algorithm of THM coupling with phase change is developed and upgraded again. The change law of failure area in one time freezing and thawing and various stability influence factors of the permafrost slope were discussed by yielding approach index. The results show that the frozen slope is local failure, from April to July is danger every year, and that the freezing temperature increment and the height of slope are still the main influence factors and that the water content, the times of freeze-thaw cycles and the temperature increment of surrounding boundary are severely affect the stability of the slope. And the research can be a significance reference for further understanding the slope stability under freeze-thaw cycles.