Dynamics of Snow Avalanches

摘要: ABSTRACT After a general introduction to snow avalanches and their consequences, type classification is discussed, schemes based on morphology, genesis magnitude are described briefly. The first technical section deals with deformation displacement of slopes prior avalanche release, the failure process, propagation initial failure. Representative values given for stress levels, gradients, volumetric deviatoric strain rates, interface glide velocity, speeds. following describes various types motion after including sliding rigid body, low-speed loose snow, high-speed dense diffused “dust clouds”, flowing slush, rolling bounding blocks clods. suggested slope angles, accelerations, flow density, driving stresses, travel velocities. third considers idealized theoretical analyses motion. Topics dealt include force, resistance, equations motion, energy power considerations, retardation runout distance, regimes, physical models. final covers dynamic forces imposed by associated “winds”. Measured impact stresses summarized, direct “wide” deduced from simple theory. Dust regarded as analogous incompressible fluids at low subsonic velocities, so that peak stagnation pressure appropriate effective density. Various interpretations surface mentioned, special attention calculation Rankine-Hugoniot conditions elastic plastic waves in snow. Forces induced interfacial shear deflection considered briefly, created winds, or “air blast”, discussed. In conclusion there simplified tabulation representative ranges, typical rates velocities processes. overall intent this review provide quantitative dynamics accordance well-established mechanical principles, avoiding unnecessary complications, controversy, specialized jargon far possible.