The failure of a weak snow layer underlying a cohesive slab is the primary step in the release process of a dry snow slab avalanche. The complex and heterogeneous microstructure of snow limits our understanding of failure initiation inside the weak layer, especially under mixed-mode shear–compression loading. Further complication arises from the dependence of snow strength on the loading rate induced by the balance between bond breaking and bond formation (sintering) during the failure process. Here, we use the discrete element method to investigate the influence of mixed-mode loading and fast sintering on the failure of a weak layer generated using cohesive ballistic deposition. Both fast and slow loading simulations resulted in a mixed-mode failure envelope in good agreement with laboratory experiments. We show that the number of broken bonds at failure and the weak layer strength significantly decreases with increasing loading angle, regardless of the loading rate. While the influence of loading rate appears negligible in shear-dominant loading (for loading angles above \(30^{\circ }\)), simulations suggest a significant increase in the weak layer strength at low loading angles and low loading rates, characteristic of natural avalanches, due to the presence of an active sintering mechanism.

中文翻译：

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雪的混合模式破坏的数值研究。

粘性平板下方弱雪层的破坏是干雪平板雪崩释放过程中的第一步。雪的复杂而异质的微观结构限制了我们对薄层内部的破坏起因的理解，尤其是在混合模式的剪切压缩载荷作用下。雪崩强度取决于破坏过程中粘结破坏和粘结形成（烧结）之间的平衡所引起的加载速率，这会使情况进一步复杂化。在这里，我们使用离散元方法研究混合模式加载和快速烧结对内聚弹道沉积产生的薄层破坏的影响。快速和慢速加载模拟都产生了与实验室实验完全吻合的混合模式失效范围。我们表明，无论加载速率如何，随着加载角度的增加，断裂时断裂的键数和薄层强度会显着降低。尽管在剪切力主导的载荷中载荷率的影响似乎可以忽略不计（对于以上载荷角\（30 ^ {\ circ} \）），模拟表明由于存在有效的烧结机制，在低加载角和低加载率下，自然崩塌的弱层强度显着增加。