1 Motivation

Alpine regions show twice the warming rate compared to the global average since the 19th century (European Environment Agency 2009), and high alpine environments are known to be particularly sensitive to temperature changes. Infrastructure which is built in permafrost-affected environments commonly suffers from a reduction in bearing capacities of affected bedrock. The overall aim of this study is to investigate the interaction of changes in bedrock properties induced by a natural decrease of permafrost and the direct effects of high alpine infrastructure.

2 Study site and infrastructure

The study site is situated around the summit station of Kitzsteinhorn cable car (3029 m a.s.l., Austria). It encompasses the north-oriented rock wall of the Kitzsteinhorn, which is made up of calcareous micaschists. The foliation is inclined approximately in the line of the slope with angles between 39° and 52°. Until the mid-20th century parts of the rock wall were covered by a permanent ice face. The current surface of the adjacent glacier is located approximately 100 m below the summit station, which was first built in 1965/66 and refurbished in 1981 and 2010. The rock wall below the summit station is permafrost affected and shows significant seasonality in rock fall activity (Hartmeyer et al. 2016). A cable car station associated with the summit station is anchored to the rock face with prestressed rock anchors.

3 Data and methods
3.1 Laboratory testing

Samples of calcareous micaschist were taken and tested extensively in laboratory. Voigtländer et al. (2014) carried out >70 tests on uniaxial compressive strength, tensile (Brazilian) strength and nondestructive tests, all on frozen and unfrozen samples. Elastic moduli, compressive and tensile strength are derived from that raw data.

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