MICROMECHANICAL APPLICATIONS TO RADIATION RECRYSTALLIZED SNOW

Buried radiation recrystallized layers are a challenging hazard to contend with in ava- lanche terrain. After forming, these layers are weak and elusive in a snow profile due to their thin struc- ture. It is difficult to accurately study these layers' mechanical properties by approximating them as a continuous medium. Adjusting the scope of the observed problem down to the micro-scale leads to some new ways to describe the mechanical behavior of snow. The evolution of the microstructure of radiation recrystallized snow was recorded with the use of micro-CT scans obtained at specific time intervals. These 3-D reconstructions allow for further analysis of the effective mechanical properties of snow. The 3-D microstructure from the micro-CT scans is used as the geometry in computer simulated mechanical tests (finite element method). This approach is advantageous since the mechanical properties of ice are known with greater precision than those of snow. Using the microstructural geometry and incorporating ice network damage, effective material properties such as stiffness and strength compare positively to macro-scale mechanical testing on non-radiation recrystallized snow. However, there is greater uncer- tai nty in the underlying material properties of the ice network for the radiation recrystallized case. There i s still more work to be done in understanding the mechanical properties of weak layers in snow is essen- tial to better quantify the hazards these layers present.