Item: An Experimental Dynamic Response Study of Hard Slab Seasonal Snow to Explosive Avalanche Hazard Mitigation
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Title: An Experimental Dynamic Response Study of Hard Slab Seasonal Snow to Explosive Avalanche Hazard Mitigation
Proceedings: Proceedings, 2012 International Snow Science Workshop, Anchorage, Alaska
Authors:
- Josephine Bones [ Department of Civil Engineering Montana State University, Bozeman, MT ]
- Daniel Miller [ Department of Civil Engineering Montana State University, Bozeman, MT ]
- Scotty Savage [ Friends of the Gallatin National Forest Avalanche Center, Bozeman, MT ]
Date: 2012
Abstract: Avalanche hazard mitigation programs routinely use explosive charges to release avalanches and test slope stability, but fundamental understanding of snowpack response to explosive detonations is lacking. This project, conducted in southwest Montana, aimed to verify past findings and further develop an understanding of snow explosive interactions, particularly for hard slab conditions. Hard slab snow poses challenges for operational avalanche programs. Past research collected dynamic snow responses 10-100m from the detonation site while the current study placed an instrumentation suite within 3-7m of the detonation. Pentolite cast boosters (0.9kg) were detonated at 0.0m, 0.5m, 1.0m, 1.5m, and 2.0m heights above the hard slab snow surface. An array of six orthogonally paired accelerometers, inserted into the snowpack at three different depths at two locations from the blast, recorded snow accelerations. High pressure sensors, located at and above the snow surface, measured air overpressures. Distances, radial and horizontal, from the explosives and charge height were scaled to TNT equivalents to aid in explosive placement comparisons. A substantial advantage was recorded in maximum snow accelerations due to elevating the explosive above the snow surface. Vertical and radial attenuation rates within the snowpack were determined. The data shows suspending charges not only increases overall response, but also increases the effective range and depth with no penalty in shock attenuation. The avalanche community benefits from this research by an advancement in understanding snow explosive interactions thereby potentially increasing avalanche programs’ safety and efficiency.
Object ID: issw-2012-142-148.pdf
Language of Article: English
Presenter(s): Unknown
Keywords: snowslope stability, avalanche control by explosives, blast bolt, hard slab,
Page Number(s): 142-148
Subjects: avalanche hazard usa ski areas instrumentation
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