The Efficacy of Frost Weathering Processes in Alpine Rockwalls
The Efficacy of Frost Weathering Processes in Alpine Rockwalls
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DOI：
10.1029/2019gl081981
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发表时间：
2019-06
影响因子：
5.2
通讯作者：
D. Draebing;M. Krautblatter
中科院分区：
文献类型：
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作者：
D. Draebing;M. Krautblatter
风化过程是高山景观演化的关键因子，也是一种危险的过程。不同的风化过程的相对重要性是很难破译的，然而，目前的知识假设在侵蚀高山岩壁冻裂的主导作用。本研究采用实验室方法模拟体积膨胀和冰离析在四个高山岩石样品，监测裂缝变形，并量化霜冻风化的功效。我们的研究结果表明，裂缝中的短期体积膨胀在数小时内提供高达10 MPa的应力，而长期冰分离在数天内产生1 MPa的应力。虽然秋季的体积膨胀可以达到临界断裂水平，但初夏的体积膨胀和冰分离更接近亚临界断裂扩展水平。我们得出结论，亚临界裂纹扩展是占主导地位的前因过程的落石开始，这可以放大罕见的临界开裂，由于体积膨胀。
Weathering processes prepare and trigger rockfall, which is a key agent of alpine landscape evolution and a hazardous process. The relative importance of different weathering processes is hard to decipher; nevertheless, current knowledge assumes a dominant role of frost cracking in eroding alpine rockwalls. This study uses a laboratory approach to simulate volumetric expansion and ice segregation in four alpine rock samples, monitors crack deformation, and quantifies frost weathering efficacy. Our results show that short‐term volumetric expansion in cracks provides stresses up to 10 MPa over hours, while long‐term ice segregation causes stresses of 1 MPa over days. While volumetric expansion in fall can reach critical fracture levels, volumetric expansion in early summer and ice segregation rather approaches subcritical fracture propagation levels. We conclude that subcritical crack propagation is the dominant antecedent process of rockfall initiation, which can be amplified by rare critical cracking due to volumetric expansion.