Abstract
As a result of mountain permafrost creep, rock glaciers are common features in high-altitude periglacial areas. From a practical point of view, beyond their localization and inventorying, both the monitoring and prediction of their evolution due to climate changes are crucial. One of the effects of climate change is the thickening of the basal shear zone (the portion of the rock glacier where most deformations are localized), eventually leading to the development of unexpected and unprecedented (in terms of location, magnitude, frequency, and timing) instability phenomena. These phenomena bear consequences for the understanding of landscape evolution, natural hazards, and the safe and sustainable operation of high-mountain infrastructures. Most of the studies about active rock glaciers are focused on the analysis of monitoring data, while just a few studies are focused on modeling their behavior to understand their possible further evolution. The active rock glacier response is characterized by a viscous (rate-dependent) behavior, influenced by seasonal temperature oscillations, and characterized by a seasonal transition from slow to fast. In this work, a new thermo-mechanical model based on the delayed plasticity theory and calibrated on experimental results is proposed. The model is employed to evaluate the influence of geometry and forcing (air temperature) on a real rock glacier (Murtèl-Corvatsch rock glacier) creep behavior.
Highlights
The main processes related to climate change in high-mountain environments involve the role of permafrost degradation in promoting slope instability
As shown in [18], in the European Alps, annual terrestrial geodetic surveys suggest that the average rock glacier surface velocity has increments of about
Temperatures inside a rock glacier are governed by heat conduction/convection processes (e.g., [19]), whose boundary conditions are the mean annual air temperature (MAAT) and the permafrost base temperature
Summary
The main processes related to climate change in high-mountain environments involve the role of permafrost degradation in promoting slope instability (amongst others, [1,2]). The first step for the solution of hydro/thermo/mechanical coupled problems is the definition of constitutive relationships capable of reproducing the material behavior To this aim, experimental laboratory tests on samples directly collected from rock glaciers (e.g., [21,28,29,30]) were performed. As a first step toward this direction, in this paper, the authors intend to introduce a simplified approach for modeling the thermo-mechanical coupled response of rock glaciers (Section 2) This is based on: (i) the introduction of a new constitutive law, conceived according to the delayed plasticity theory proposed in [40], for describing the mechanical behavior of ice-rock mass mixtures (Section 2.1), (ii) the solution of the heat diffusion equation (Section 2.2) and (iii) the schematization of the rock glacier into a one-dimensional problem (Section 2.3).
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