SYSTEMATIC MECHANICAL MODEL BUILDING IN PERMAFROST ROCKS

Warming rate in the European Alps has been twice the global average since the 19th century. Warming of permafrost-affected high-alpine rock walls can reduce bedrock bearing capacities and rock wall stability and thus endanger humans and infrastructure. Rock and ice mechanics are not fully understood and currently no general approach exists to (1) identify stability-relevant effects and parameters, (2) choose a suitable numerical model setup, and (3) parameterize the model with respect to space and time.

The presented research integrates permafrost-related changes in high-alpine rockwalls into a numerical model to calculate rock slope stability. The aim is to create a mechanical modelling framework to depict permafrost-influenced systems in a simple yet sufficiently precise way to consider all long-term relevant factors in the calculations.

Setting up a numerical model for the mechanical behaviour of permafrost rocks requires an adequate understanding of the influencing factors (scales, rock temperature, ice and water content, interannual variations and their long term effects,...). Subsequently, the suitable modelling approach, parameter sets and model stages can be chosen to set up a representative mechanical and numerical model.

The proposed general modelling procedure integrates conventional rock mechanics, rock-ice mechanical influences and stages of the mechanical system on its destabilisation path (temperature-dependent rock and ice properties, redistribution of load due to rock bridge weakening,...). It is then demonstrated on permafrost rock slopes in the Austrian Alps.