Item: Quantified loaded column stability test: mechanics, methodology, & preliminary trials
Title: Quantified loaded column stability test: mechanics, methodology, & preliminary trials
Proceedings: Proceedings of the 2000 International Snow Science Workshop, October 1-6, Big Sky, Montana
Authors: Christopher C. Landry, John J. Borkowski, Robert L. Brown, Montana State University at Bozeman, Montana, USA
Abstract: Avalanche forecasters have employed ad-hoc "collapse" (loaded column) stability tests for decades, stacking blocks of snow on top of an isolated column until the column collapses and/or fractures in shear. This study presents a more rigorous "quantified loaded column tesf' methodology, and preliminary analyses of the test method. An isolated vertical column of snow is cut, on a slope, using a plywood load plate of 0.04 m2 or 0.08 m2 as a template. One of two test modes is employed, depending on the depth of the weak layer. Vertical load is applied to the column at the areal center of the load plate using a mechanical force gauge. Each load increment of 2.0 kg over 0.08 m2, or of 1.0 kg over 0.04 m2, is equivalent to 25 mm Of water. Loading is "rapid" in order to generate brittle shear fracture at the weakest slab/weak layer boundary. Net shear stress (N/m2) at fracture is computed and a stability ratio is calculated, diViding shear stress at fracture by in-situ shear stress at the base of the slab. Test variability and plate-size effect were investigated in trials during the 1999/2000 season. Side-by side trials were performed where the quantified loaded column test was compared to the shear frame.
Keywords: avalanche forecasting, stability test
Digital Abstract Not Available