Designing infrastructure and assessing hazard for risks mapping in mountainous environments is a challenging task for every engineer and geoscientist. Steep and sometimes unstable terrain, heterogeneous geological settings, harsh climatic conditions with strong winds, rain, snow (including drifts and significant snow loads) and large temperature variations between summer and winter play key roles in the design process. Not only is a structure directly influenced by these factors in terms of foundation conditions, for example, but also indirectly by rock fall, debris flows or snow avalanches. The difficulties related to foundations in permafrost are largely controlled by the fact that the ground is frozen and may contain ice in various forms, such as ice rich layers, pore ice in coarse soils, ice lenses in fine soils or ice-filled joints in fractured rocks. The ground ice is the main problem affecting mountain infrastructure due to its susceptibility to creep, accrete and melt, hence changing the soil structure. In addition, the top layer thaws during the summer months further changing the strength and deformation characteristics of the ground. Climate change adds even more uncertainties to the foundation and load conditions of any mountainous infrastructure in the long term and needs to be addressed early in the design process. The ground is therefore in a transient state that has to be considered and characterised adequately.

Unique geotechnical characteristics and important features of permafrost soils and rocks, which focus on mountain permafrost, are highlighted related to the design and the construction of mountain infrastructure. The main objective of this chapter is to help with the design process, prolong the service life of structures and to lower the risks and damage potential when dealing with infrastructure located in, or in the proximity of, mountain permafrost environments.

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