- Fabrizio Barpi, Politecnico di Torino
- Gianmarco Vallero, Politecnico di Torino
- Monica Barbero, Politecnico di Torino
- Mauro Borri-Brunetto, Politecnico di Torino
- Valerio De Biagi, Politecnico di Torino
Snow is a complex, multi-phase and high-porosity natural material whose mechanical behavior at the macroscopic scale of observation is strongly influenced by the peculiar characteristics of its microstructure. Moreover, snow can be considered as a "hot material" because, in many terrestrial environments, exists at temperatures that are very close to its melting point. Therefore, as soon as snowflakes deposit over the ground, they are first subjected to mechanical-induced shape modification and then to thermal-induced changes (i.e., snow metamorphisms) that transform the single sharpened precipitation particles in more complicated interconnected structures. The physical and mechanical properties of metamorphosed snow are thus determined by the shape of the crystals (or grains) and the connections between them (sintering bonds). All these issues, coupled with the fact that layers of snow with different properties are usually present in a snowpack, are at the basis of the comprehension of the mechanical response of snow to external actions and should be taken into account in several different application fields. Snow, indeed, is a natural resource which is essential for alpine ecosystem as well as for winter tourism and sports, but on the other hand is a critical element to be considered in the design of structures and infrastructures in alpine and cold environments. Moreover, snow avalanches represent one of the main hazards in mountain areas, that can potentially endanger human lives, economical activities, structures, and also historical and natural heritages.
To investigate the multifaceted aspects of the mechanical behavior of snow and to deal with such a wide range of engineering applications, a more and more crucial role was assumed by computational and numerical methods. With the emergence of high-performance computers and the optimization of specific software, computational methods can deal with several types of complex problems such as large deformations, multiphysics, multi-phase media, etc.
As a brief overlook of the state-of-the-art of computational mechanics applied to snow, the numerical analyses based on Finite Element Method (FEM) are generally adopted within the field of Continuum Mechanics to reproduce laboratory tests and to calibrate reliable constitutive models typically based on elasto-plastic theory. Therefore, specific and detailed numerical tools are needed to properly depict snow specific features, such as the integration of the flow rule, the hardening/softening law, etc. Other types of problems involving snow can be faced by using different solutions. For instance, the failure of a weak interface layer which generates between two stiffer snow slabs is often investigated through the Distinct Element Method (DEM) or the Fiber-Bundle Model (FBM). The former allows to take into account the different characteristics of the snow microstructure and also to model the rupture of the bonds between them by using simple contact models, while the latter models the whole heterogeneous snow layer as an equivalent series of simple structural elements, i.e., the 1D visco-elasto-plastic fibers. In the last two decades, more advanced and promising algorithms, the so-called "point-based methods", were introduced in the field of porous and granular media. These methods, e.g. the Material Point Method (MPM) and the Smoothed Particle Hydrodynamics (SPH), allow to overcome the problems that traditional mesh-based numerical methods generally suffer (i.e., mesh distortion, missed convergence, etc.). Therefore, MPM and SPH, as well as their further developments, could be able to face more complex processes involving snow, such as heat flux or water flow developing into the snow microstructure, melting and re-crystallization, temperature-deformation relations, localization and bifurcation, etc.
The aim of this mini-symposium is therefore to provide researchers an opportunity to share their experiences on these topics and discuss their research and findings. The multidisciplinary discussion is indeed at the basis of the scientific process and progress, especially when it comes to natural materials. For these reasons, the proponents of this mini-symposium intend to involve researchers with different know-how, who wish to share their experiences both in practice and in theoretical and experimental fields, so as to provide a sensible contribution to snow mechanics research.