Influences of Snow Cover on Thermal and Mechanical Processes in steep Permafrost Rock Walls
Degradation of rock permafrost can cause instability due to influences on rock- and ice-mechanical properties. Permafrost conditions can be altered by thermal processes and, thus, also mechanical properties of rocks. Snow cover controls the seasonal occurrence of thermal processes. A conceptual appr...
Main Author: | |
---|---|
Other Authors: | , |
Format: | Doctoral or Postdoctoral Thesis |
Language: | English |
Published: |
Universitäts- und Landesbibliothek Bonn
2015
|
Subjects: | |
Online Access: | https://hdl.handle.net/20.500.11811/6386 |
id |
ftunivbonn:oai:bonndoc.ulb.uni-bonn.de:20.500.11811/6386 |
---|---|
record_format |
openpolar |
spelling |
ftunivbonn:oai:bonndoc.ulb.uni-bonn.de:20.500.11811/6386 2023-05-15T16:36:49+02:00 Influences of Snow Cover on Thermal and Mechanical Processes in steep Permafrost Rock Walls Draebing, Daniel Dikau, Richard Krautblatter, Michael 2015-02-24 application/pdf https://hdl.handle.net/20.500.11811/6386 eng eng Universitäts- und Landesbibliothek Bonn info:eu-repo/semantics/altIdentifier/urn/urn:nbn:de:hbz:5n-38536 https://hdl.handle.net/20.500.11811/6386 In Copyright http://rightsstatements.org/vocab/InC/1.0/ openAccess Permafrost Felsstabilität Schneedecke Thermale Prozesse Felsmechanische Prozesse Rock Stability Snow Cover Thermal Processes Rock Mechanical Processes ddc:550 doc-type:doctoralThesis 2015 ftunivbonn https://doi.org/20.500.11811/6386 2023-02-13T19:27:48Z Degradation of rock permafrost can cause instability due to influences on rock- and ice-mechanical properties. Permafrost conditions can be altered by thermal processes and, thus, also mechanical properties of rocks. Snow cover controls the seasonal occurrence of thermal processes. A conceptual approach is presented to explain snow cover influences on steep permafrost rock walls. This approach combines snow cover with thermal and mechanical processes. To support the conceptual approach, empirical data is presented to evaluate snow cover, the thermal and the mechanical regime. A combination of temperature data loggers, photos of automatic cameras and avalanche probe measurements allows the reconstruction of the temporal and spatial development of snow cover. Four snow stages can be distinguished and an overall cooling effect derived. In laboratory measurements, p-wave velocities of 22 different alpine rocks are tested and the influence of ice pressure on seismic velocities is evaluated. P-wave velocity increases dependent on lithology due to freezing and increase is dominated by an increase of the velocity of the rock matrix due to ice pressure. These findings are incorporated into a novel time-average equation and provide the basis for the applicability of refraction seismics in permafrost rock walls. The influence of snow cover on the thermal regime was investigated with the use of Seismic Refraction Tomography (SRT), Electrical Resistivity Tomography (ERT) and thermal modelling. Long lasting snow cover in 2013 delayed heat transport processes by insulating the underground and prevented active-layer thaw while snow cover absence resulted in deep thawing in 2012. Thus, snow cover plays a key role of permafrost evolution on slope facet scale. Snow cover is the main controlling factor of discontinuity movement and rock decay. The snow cover controls the occurrence of thermal expansion/contraction and volumetric expansion as it prevents these processes, while favouring ice segregation due to isolation. Volumetric ... Doctoral or Postdoctoral Thesis Ice permafrost bonndoc - The Repository of the University of Bonn |
institution |
Open Polar |
collection |
bonndoc - The Repository of the University of Bonn |
op_collection_id |
ftunivbonn |
language |
English |
topic |
Permafrost Felsstabilität Schneedecke Thermale Prozesse Felsmechanische Prozesse Rock Stability Snow Cover Thermal Processes Rock Mechanical Processes ddc:550 |
spellingShingle |
Permafrost Felsstabilität Schneedecke Thermale Prozesse Felsmechanische Prozesse Rock Stability Snow Cover Thermal Processes Rock Mechanical Processes ddc:550 Draebing, Daniel Influences of Snow Cover on Thermal and Mechanical Processes in steep Permafrost Rock Walls |
topic_facet |
Permafrost Felsstabilität Schneedecke Thermale Prozesse Felsmechanische Prozesse Rock Stability Snow Cover Thermal Processes Rock Mechanical Processes ddc:550 |
description |
Degradation of rock permafrost can cause instability due to influences on rock- and ice-mechanical properties. Permafrost conditions can be altered by thermal processes and, thus, also mechanical properties of rocks. Snow cover controls the seasonal occurrence of thermal processes. A conceptual approach is presented to explain snow cover influences on steep permafrost rock walls. This approach combines snow cover with thermal and mechanical processes. To support the conceptual approach, empirical data is presented to evaluate snow cover, the thermal and the mechanical regime. A combination of temperature data loggers, photos of automatic cameras and avalanche probe measurements allows the reconstruction of the temporal and spatial development of snow cover. Four snow stages can be distinguished and an overall cooling effect derived. In laboratory measurements, p-wave velocities of 22 different alpine rocks are tested and the influence of ice pressure on seismic velocities is evaluated. P-wave velocity increases dependent on lithology due to freezing and increase is dominated by an increase of the velocity of the rock matrix due to ice pressure. These findings are incorporated into a novel time-average equation and provide the basis for the applicability of refraction seismics in permafrost rock walls. The influence of snow cover on the thermal regime was investigated with the use of Seismic Refraction Tomography (SRT), Electrical Resistivity Tomography (ERT) and thermal modelling. Long lasting snow cover in 2013 delayed heat transport processes by insulating the underground and prevented active-layer thaw while snow cover absence resulted in deep thawing in 2012. Thus, snow cover plays a key role of permafrost evolution on slope facet scale. Snow cover is the main controlling factor of discontinuity movement and rock decay. The snow cover controls the occurrence of thermal expansion/contraction and volumetric expansion as it prevents these processes, while favouring ice segregation due to isolation. Volumetric ... |
author2 |
Dikau, Richard Krautblatter, Michael |
format |
Doctoral or Postdoctoral Thesis |
author |
Draebing, Daniel |
author_facet |
Draebing, Daniel |
author_sort |
Draebing, Daniel |
title |
Influences of Snow Cover on Thermal and Mechanical Processes in steep Permafrost Rock Walls |
title_short |
Influences of Snow Cover on Thermal and Mechanical Processes in steep Permafrost Rock Walls |
title_full |
Influences of Snow Cover on Thermal and Mechanical Processes in steep Permafrost Rock Walls |
title_fullStr |
Influences of Snow Cover on Thermal and Mechanical Processes in steep Permafrost Rock Walls |
title_full_unstemmed |
Influences of Snow Cover on Thermal and Mechanical Processes in steep Permafrost Rock Walls |
title_sort |
influences of snow cover on thermal and mechanical processes in steep permafrost rock walls |
publisher |
Universitäts- und Landesbibliothek Bonn |
publishDate |
2015 |
url |
https://hdl.handle.net/20.500.11811/6386 |
genre |
Ice permafrost |
genre_facet |
Ice permafrost |
op_relation |
info:eu-repo/semantics/altIdentifier/urn/urn:nbn:de:hbz:5n-38536 https://hdl.handle.net/20.500.11811/6386 |
op_rights |
In Copyright http://rightsstatements.org/vocab/InC/1.0/ openAccess |
op_doi |
https://doi.org/20.500.11811/6386 |
_version_ |
1766027141060755456 |