A two‐phase mechanical model for rock‐ice avalanches
A two‐phase mechanical model for rock‐ice avalanches
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DOI：
10.1002/2014jf003183
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发表时间：
2014-10
期刊：
影响因子：
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通讯作者：
S. Pudasaini;M. Krautblatter
中科院分区：
文献类型：
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作者：
S. Pudasaini;M. Krautblatter
岩冰雪崩事件是上个世纪最危险的自然灾害之一。与岩石雪崩相反，固体相（冰）可以在岩石-冰雪崩过程中转化为流体，并从根本上改变机械过程。一个真实的两相泥石流模型可以更好地解决固体（岩石和冰）和流体（水，雪，泥浆和细颗粒）的动态相互作用比目前使用的单相Voellmy或库仑型模型。我们提出了一个两相模型，能够执行动态强度削弱由于内部流化和基础润滑和内部质量和动量交换的阶段。有效的基础和内部摩擦角是可变的，并对应于不断变化的有效固体体积分数，摩擦系数，冰的体积分数，真正的摩擦系数，润滑和流化因子。基准数值模拟表明，两相模型能够解释发生在内部和沿流路沿着流动的岩冰雪崩的动态变化的摩擦特性，相间的质量和动量交换能够演示前端浪涌头和多个其他浪涌在碎片体的机制.这是在真实的两相泥石流中观察到的现象，但在这里是通过应用两相质量流模型新模拟的。相之间的质量和动量交换以及相关的内部和基底强度减弱控制了异常长的跳动距离，特别是在雪崩的关键初始和传播阶段提供了更真实的模拟，并解释了岩石-冰雪崩异常高和动态变化的流动性。
Rock‐ice avalanche events are among the most hazardous natural disasters in the last century. In contrast to rock avalanches, the solid phase (ice) can transform to fluid during the course of the rock‐ice avalanche and fundamentally alter mechanical processes. A real two‐phase debris flow model could better address the dynamic interaction of solid (rock and ice) and fluid (water, snow, slurry, and fine particles) than presently used single‐phase Voellmy‐ or Coulomb‐type models. We present a two‐phase model capable of performing dynamic strength weakening due to internal fluidization and basal lubrication and internal mass and momentum exchanges between the phases. Effective basal and internal friction angles are variable and correspond to evolving effective solid volume fraction, friction factors, volume fraction of the ice, true friction coefficients, and lubrication and fluidization factors. Benchmark numerical simulations demonstrate that the two‐phase model can explain dynamically changing frictional properties of rock‐ice avalanches that occur internally and along the flow path. The interphase mass and momentum exchanges are capable of demonstrating the mechanics of frontal surge head and multiple other surges in the debris body. This is an observed phenomenon in a real two‐phase debris flow, but newly simulated here by applying the two‐phase mass flow model. Mass and momentum exchanges between the phases and the associated internal and basal strength weakening control the exceptional long runout distances, provide a more realistic simulation especially during the critical initial and propagation stages of avalanche, and explain the exceptionally high and dynamically changing mobility of rock‐ice avalanches.