Item: Fracture character in compression tests
Title: Fracture character in compression tests
Proceedings: Proceedings of the 2004 International Snow Science Workshop, Jackson Hole, Wyoming
Authors: Alec van Herwijnen and Bruce Jamieson, Dept. of Civil Engineering, Dept. of Geology and Geophysics
Abstract: Stability tests are widely used to identify and qualify potential failure layers for slab avalanches. As an addition to stability test scores, some avalanche safety programs have recorded the character of fractures for many years. Researchers at the University of Calgary have been systematically classifying fractures in compression and rutschblock tests since the winter of 1996-97. The classification system was refined in December 2002 and presently comprises five categories: Progressive Compression (PC), Resistant Planar (RP), Sudden Planar (SP), Sudden Collapse (SC) and non-planar Break (B). Some 4621 fractures were classified in over 2200 compression tests performed at study slopes in the Columbia Mountains of British Columbia, Canada. Of these, more than 1000 compression tests were performed on recently skier-tested slopes. Specific snowpack characteristics, including hardness difference and difference in crystal size across the failure layer, associated with the different fracture characters were identified. Data from skier-tested slopes show that fracture characterization can improve the interpretation of compression test results. Sudden fractures (Sudden Collapse and Sudden Planar) are more often the failure layer of slab avalanches than other fractures. Furthermore, limited observations suggest that the evolution of fracture character for weak layers can provide information on the potential for skier-triggered dry slab avalanches to occur.
Keywords: stability test, avalanche forecasting, fracture initiation, fracture propagation, stability evaluation
Digital Abstract Not Available