Risk associated to avalanches is progressively increasing due to recent climatic changes and an improper use of the alpine environment. In our country, vulnerability and hazard reduction measures are widespread adopted for people safety and land protection aims. Nevertheless, specific normative tools are still inadequate for what concerns both the design of defense structures and the regulation of land use. A better comprehension of the deformation behaviour of snow would be of valuable help in the analysis of snow-related engineering problems. To this aim, a constitutive approach is suggested for dry granular snow, starting from the analysis of published experimental data. The literature review highlights that the deformation mechanisms acting at the microscale level play a fundamental role in the strongly time-dependent and rate-sensitive macroscopic behaviour. Suitable constitutive models may be conceived in the framework of elasto-viscoplasticity and they should account for the coupled effects of chemical bonding due to sintering and mechanical degradation. A novel analytical expression is proposed to describe the temporal evolution of bonding, on the basis of experimental data concerning sintering of ice spheres. A general conceptual framework is suggested, and a basic constitutive model is proposed and verified against published experimental data. The comparison between numerical simulations and experimental data shows the good capabilities of the model to reproduce correctly most of the significant features of the mechanical behaviour of snow under different loading paths.
Risk associated to avalanches …
AUTORI: Cresseri S., Jommi C. RIG ANNO: 2004 NUMERO: 4 Numero di pagina: 43