A temperature-dependent mechanical model to assess the stability of degrading permafrost rock slopes
<p>Over the last 2 decades, permafrost degradation has been observed to be a major driver of enhanced rock slope instability and associated hazards in high mountains. While the thermal regime of permafrost degradation in high mountains has been addressed in several modelling approaches, no mec...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2021-09-01
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| Series: | Earth Surface Dynamics |
| Online Access: | https://esurf.copernicus.org/articles/9/1125/2021/esurf-9-1125-2021.pdf |
| _version_ | 1819131085601112064 |
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| author | P. Mamot S. Weber S. Eppinger M. Krautblatter |
| author_facet | P. Mamot S. Weber S. Eppinger M. Krautblatter |
| author_sort | P. Mamot |
| collection | DOAJ |
| description | <p>Over the last 2 decades, permafrost degradation has been observed to be a major driver of enhanced rock slope instability and associated hazards in high mountains. While the thermal regime of permafrost degradation in high mountains has been addressed in several modelling approaches, no mechanical models that thoroughly explain rock slope destabilisation controls in degrading permafrost have been developed. Meanwhile, recent
laboratory studies have shown that degrading permafrost affects both, rock and
ice mechanical strength parameters as well as the strength of rock–ice
interfaces. This study presents a first general approach for a
temperature-dependent numerical stability model that simulates the
mechanical response of a warming and thawing permafrost rock slope. The
proposed procedure is exemplified using a rockslide at the permafrost-affected Zugspitze summit crest. Laboratory tests on frozen and
unfrozen rock joint and intact rock properties provide material parameters
for discontinuum models developed with the Universal Distinct Element Code (UDEC). Geophysical and geotechnical field surveys reveal information on permafrost distribution and the fracture network. This model can demonstrate how warming decreases rock slope stability to a critical level and why thawing initiates failure. A generalised sensitivity analysis of the model with a simplified geometry and warming trajectory below 0 <span class="inline-formula"><sup>∘</sup></span>C shows that progressive warming close to the melting point initiates instability above a critical slope angle of 50–62<span class="inline-formula"><sup>∘</sup></span>, depending on the orientation of the fracture network. The increase in displacements intensifies for warming steps closer to 0 <span class="inline-formula"><sup>∘</sup></span>C. The simplified and generalised model can be applied to permafrost rock slopes (i) which warm above <span class="inline-formula">−4</span> <span class="inline-formula"><sup>∘</sup></span>C, (ii) with ice-filled joints, (iii) with fractured limestone or probably most of the rock types relevant for permafrost rock slope failure, and (iv) with a wide range of slope angles (30–70<span class="inline-formula"><sup>∘</sup></span>) and orientations of the fracture network (consisting of three joint sets). Here, we present a benchmark model capable of assessing the future destabilisation of degrading permafrost rock slopes.</p> |
| first_indexed | 2024-12-22T09:09:54Z |
| format | Article |
| id | doaj.art-8774097d3fc54b98a64af98dddaf909a |
| institution | Directory Open Access Journal |
| issn | 2196-6311 2196-632X |
| language | English |
| last_indexed | 2024-12-22T09:09:54Z |
| publishDate | 2021-09-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Earth Surface Dynamics |
| spelling | doaj.art-8774097d3fc54b98a64af98dddaf909a2022-12-21T18:31:29ZengCopernicus PublicationsEarth Surface Dynamics2196-63112196-632X2021-09-0191125115110.5194/esurf-9-1125-2021A temperature-dependent mechanical model to assess the stability of degrading permafrost rock slopesP. MamotS. WeberS. EppingerM. Krautblatter<p>Over the last 2 decades, permafrost degradation has been observed to be a major driver of enhanced rock slope instability and associated hazards in high mountains. While the thermal regime of permafrost degradation in high mountains has been addressed in several modelling approaches, no mechanical models that thoroughly explain rock slope destabilisation controls in degrading permafrost have been developed. Meanwhile, recent laboratory studies have shown that degrading permafrost affects both, rock and ice mechanical strength parameters as well as the strength of rock–ice interfaces. This study presents a first general approach for a temperature-dependent numerical stability model that simulates the mechanical response of a warming and thawing permafrost rock slope. The proposed procedure is exemplified using a rockslide at the permafrost-affected Zugspitze summit crest. Laboratory tests on frozen and unfrozen rock joint and intact rock properties provide material parameters for discontinuum models developed with the Universal Distinct Element Code (UDEC). Geophysical and geotechnical field surveys reveal information on permafrost distribution and the fracture network. This model can demonstrate how warming decreases rock slope stability to a critical level and why thawing initiates failure. A generalised sensitivity analysis of the model with a simplified geometry and warming trajectory below 0 <span class="inline-formula"><sup>∘</sup></span>C shows that progressive warming close to the melting point initiates instability above a critical slope angle of 50–62<span class="inline-formula"><sup>∘</sup></span>, depending on the orientation of the fracture network. The increase in displacements intensifies for warming steps closer to 0 <span class="inline-formula"><sup>∘</sup></span>C. The simplified and generalised model can be applied to permafrost rock slopes (i) which warm above <span class="inline-formula">−4</span> <span class="inline-formula"><sup>∘</sup></span>C, (ii) with ice-filled joints, (iii) with fractured limestone or probably most of the rock types relevant for permafrost rock slope failure, and (iv) with a wide range of slope angles (30–70<span class="inline-formula"><sup>∘</sup></span>) and orientations of the fracture network (consisting of three joint sets). Here, we present a benchmark model capable of assessing the future destabilisation of degrading permafrost rock slopes.</p>https://esurf.copernicus.org/articles/9/1125/2021/esurf-9-1125-2021.pdf |
| spellingShingle | P. Mamot S. Weber S. Eppinger M. Krautblatter A temperature-dependent mechanical model to assess the stability of degrading permafrost rock slopes Earth Surface Dynamics |
| title | A temperature-dependent mechanical model to assess the stability of degrading permafrost rock slopes |
| title_full | A temperature-dependent mechanical model to assess the stability of degrading permafrost rock slopes |
| title_fullStr | A temperature-dependent mechanical model to assess the stability of degrading permafrost rock slopes |
| title_full_unstemmed | A temperature-dependent mechanical model to assess the stability of degrading permafrost rock slopes |
| title_short | A temperature-dependent mechanical model to assess the stability of degrading permafrost rock slopes |
| title_sort | temperature dependent mechanical model to assess the stability of degrading permafrost rock slopes |
| url | https://esurf.copernicus.org/articles/9/1125/2021/esurf-9-1125-2021.pdf |
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