Interaction of thermal and mechanical processes in steep permafrost rock walls: A conceptual approach
Interaction of thermal and mechanical processes in steep permafrost rock walls: A conceptual approach
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DOI：
10.1016/j.geomorph.2014.08.009
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发表时间：
2014-12
期刊：
影响因子：
3.9
通讯作者：
D. Draebing;M. Krautblatter;R. Dikau
中科院分区：
文献类型：
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作者：
D. Draebing;M. Krautblatter;R. Dikau
多年冻土岩墙的退化降低了岩质边坡的稳定性，并可能引发各种程度的边坡失稳。岩石失稳是由剪切力和剪切阻力的平衡控制的。边坡稳定性对升温的敏感性是由剪切力和阻力的复杂相互作用引起的。传导、对流和平流热输运过程可使岩壁中的冻土升温、退化和融化。在季节尺度上，积雪变化是一个知之甚少的关键控制解冻和冻土退化的时间和程度。我们确定了两个潜在的临界时间窗口，剪切力可能超过剪切阻力的岩石。在初夏，流体静压和低温静压的组合可以导致剪切力超过高冻结剪切阻力的峰值，并且在秋季，快速增加的剪切力可以超过缓慢增加的剪切阻力。在一个多年系统尺度上，剪切阻力的变化主要是岩石机械冰机械控制。岩桥的破坏会导致对变暖的敏感性增加。气候变化改变了积雪和持续时间，从而改变了岩壁中的热和机械过程。多年冻土融化的扩大将导致更高的岩石边坡失稳和岩石崩塌活动。我们提出了一个整体的概念方法连接热和机械过程，验证部分模型与地球物理和运动学数据和开发未来的场景，以提高对系统规模的理解。
Degradation of permafrost rock wall decreases stability and can initiate rock slope instability of all magnitudes. Rock instability is controlled by the balance of shear forces and shear resistances. The sensitivity of slope stability to warming results from a complex interplay of shear forces and resistances. Conductive, convective and advective heat transport processes act to warm, degrade and thaw permafrost in rock walls. On a seasonal scale, snow cover changes are a poorly understood key control of the timing and extent of thawing and permafrost degradation. We identified two potential critical time windows where shear forces might exceed shear resistances of the rock. In early summer combined hydrostatic and cryostatic pressure can cause a peak in shear force exceeding high frozen shear resistance and in autumn fast increasing shear forces can exceed slower increasing shear resistance. On a multiannual system scale, shear resistances change from predominantly rock-mechanically to ice-mechanically controlled. Progressive rock bridge failure results in an increase of sensitivity to warming. Climate change alters snow cover and duration and, hereby, thermal and mechanical processes in the rock wall. Amplified thawing of permafrost will result in higher rock slope instability and rock fall activity. We present a holistic conceptual approach connecting thermal and mechanical processes, validate parts of the model with geophysical and kinematic data and develop future scenarios to enhance understanding on system scale.