Dynamics of glide avalanches and snow gliding

Abstract

In recent years, due to warmer snow cover, there has been a significant increase in the number of cases of damage caused by gliding snowpacks and glide avalanches. On most occasions, these have been full-depth, wet-snow avalanches, and this led some people to express their surprise: how could low-speed masses of wet snow exert sufficiently high levels of pressure to severely damage engineered structures designed to carry heavy loads? This paper reviews the current state of knowledge about the formation of glide avalanches and the forces exerted on simple structures by a gliding mass of snow. One particular difficulty in reviewing the existing literature on gliding snow and on force calculations is that much of the theoretical and phenomenological analyses were presented in technical reports that date back to the earliest developments of avalanche science in the 1930s. Returning to these primary sources and attempting to put them into a contemporary perspective are vital. A detailed, modern analysis of them shows that the order of magnitude of the forces exerted by gliding snow can indeed be estimated correctly. The precise physical mechanisms remain elusive, however. We comment on the existing approaches in light of the most recent findings about related topics, including the physics of granular and plastic flows, and from field surveys of snow and avalanches (as well as glaciers and debris flows). Methods of calculating the forces exerted by glide avalanches are compared quantitatively on the basis of two case studies. This paper shows that if snow depth and density are known, then certain approaches can indeed predict the forces exerted on simple obstacles in the event of glide avalanches or gliding snow cover.

A new CT scan methodology to characterize a small aggregation gravel clast contained in a soft sediment matrix

“…The second main type of input can be attributed to wetsnow avalanches that occur mostly over springtime. Wetsnow avalanches are typically observed in steep alpine valleys where the slope exceeds 28 • , but they have been observed on slopes as low as 15 • (Jomelli and Bertran, 2001;Ancey and Bain, 2015). They are capable of transporting sediments ranging in size from fine eolian particles up to cobbles or boulders (van Steijn et al, 1995;Blikra and Nemec, 1998;Jomelli et al, 2007;Saemundsson et al, 2008;Van Steijn, 2011).…”

Determining the drivers for snow gliding

“…Both the vegetation and the microrelief depend on the land use, which is an input for snow-glide modeling (Leitinger et al, 2008;Maggioni et al, 2016). Bartelt et al (2012) developed a two-dimensional viscoelastic continuum model to specify the start of gliding snow avalanches. Ancey and Bain (2015) summarized the knowledge concerning the formation of snow-glide avalanches and its impact on obstacles in the path.…”

“…Bartelt et al (2012) developed a two-dimensional viscoelastic continuum model to specify the start of gliding snow avalanches. Ancey and Bain (2015) summarized the knowledge concerning the formation of snow-glide avalanches and its impact on obstacles in the path. They concluded that meteorological conditions and topographic features causing snow gliding are well known, but the mechanisms are poorly understood.…”

Runout Scaling and Deposit Morphology of Rapid Mudflows

“…This idealization applies to flows of saturated plastic soil with a high content of water and fines, which are known as mudflows (Hungr et al, ). It is also relevant to muddy debris flows (Kaitna et al, ; Takahashi, ), snow avalanches (Ancey & Bain, ; Kern et al, ), and lahars and lava flows (Sakimoto & Gregg, ), which exhibit a similar macroscopic behavior except for a different temperature dependency of viscosity (Balmforth et al, ; Griffiths, ). Submarine landslides with mainly saturated fine materials, where the ambient fluid is the same as the interstitial fluid, also fall into this category (Zakeri et al, , ).…”