Detection and quantification of permafrost change in alpine rock walls and implications for rock instability [Elektronische Ressource] / vorgelegt von Michael Krautblatter

Michael Krautblatter

Informations

• Publié par: rheinische_friedrich-wilhelms-universitat_bonn
• Publié le: 01 janvier 2009
• Nombre de lectures: 6
• Langue: English
• Poids de l'ouvrage: 23 Mo

Extrait

Even things that are true
can be proved
(Oscar Wilde)







Gewidmet meinen Eltern, Harald, Stephan und Ronja für ihre stetige Unterstützung. Geographisches Institut der Universität Bonn

Detection and quantification of permafrost
change in alpine rock walls
and implications for rock instability
Dissertation

zur Erlangung des Doktorgrades (Dr. rer. nat.)
der
Mathematisch-Naturwissenschaftlichen Fakultät
der
Rheinischen Friedrich-Wilhelms-Universität Bonn
vorgelegt von
Michael Krautblatter
aus
Erlangen
Bonn, den 9.3.2009
1Angefertigt mit Genehmigung der Mathematisch-Naturwissenschaftlichen Fakultät
der Rheinischen Friedrich-Wilhelms-Universität Bonn


Gutachter: 1. Prof. Dr. R. Dikau
2. Prof. Dr. W. Haeberli
3. Prof. Dr. A. Kemna
4. Prof. Dr. M. Moser

Datum der Promotion: 1. Juli 2009



Comment:
thThis Ph.D.-thesis was written in accordance with the rules for “Kumulative Dissertationen” issued on the 12 of December,
2008. Text of articles is printed in the original version in American English. The letter of acceptance for “Krautblatter et al.,
accepted” arrived too late to include the revision and, thus, the submitted version is presented. The following articles have
been incorporated in the thesis:
- Krautblatter, M. and Zisser, N. (submitted): Laboratory evidence for linear temperature-resistivity pathways of
thawed, supercooled and frozen permafrost rocks. Geophysical Research Letters.
- Krautblatter and Hauck (2007). Electrical resistivity tomography monitoring of permafrost in solid rock walls.
Journal of Geophysical Research, Earth-Surface. Vol. 112(F2), doi: 10.1029/2006JF000546.
- Krautblatter (2009). Patterns of multiannual aggradation of permafrost in rock walls with and without hydraulic
interconnectivity (Steintälli, Valley of Zermatt, Swiss Alps). Lecture Notes in Earth Sciences. Vol 115: 199-219.
- Krautblatter, M., Verleysdonk, V., Flores-Orozco, A. and Kemna, A. (accepted): Quantitative temperature-calibrated
imaging of seasonal changes in permafrost rock walls by high-resolution ERT and implications for rock slope sta-
bility (Zugspitze, German/Austrian Alps). Journal of Geophysical Research, Earth-Surface.
- Krautblatter (2008). Rock Permafrost Geophysics and its Explanatory Power for Permafrost-Induced Rockfalls and
Rock Creep: a Perspective. Paper presented at the 9th Int. Conf. on Permafrost, Fairbanks, Alaska, US: 999-1004.
2Contents:
1 Abstract........................................................................................................................................................... 7
2 Zusammenfassung ......................................................................................................................................... 9
3 Introduction...................................................................................................................................................11
4 Hypotheses.................................................................................................................................................... 13
4.1 Theory .................................................................................................................................................. 13
4.2 Methodology ........................................................................................................................................ 13
4.3 System understanding......................................................................................................................... 13
5 Rock permafrost: a systems approach ......................................................................................................... 14
5.1 Thermal properties ............................................................................................................................. 15
5.1.1 Basic system.................................................................................................................................. 16
5.1.2 External heat fluxes....................................................................................................................... 16
5.1.2.1 Long-wave and short-wave radiation ........................................................................................ 16
5.1.2.2 Sensible and latent surface heat fluxes...................................................................................... 18
5.1.2.3 Geothermal and transient thermal fluxes................................................................................... 19
5.1.3 Internal heat uptake and transmission ........................................................................................... 20
5.1.3.1 Basic sensitive system............................................................................................................... 20
5.1.3.2 Spatial dimension ...................................................................................................................... 20
5.1.3.3 Latent phase transitions............................................................................................................. 21
5.1.3.4 Discontinuous heat flow............................................................................................................ 21
5.1.3.5 Heat transfer in clefts ................................................................................................................ 22
5.1.3.6 Feedbacks.................................................................................................................................. 22
5.1.3.7 Response times.......................................................................................................................... 23
5.1.4 Empiric data .................................................................................................................................. 23
5.1.4.1 Rock surface temperatures and extrapolation of thaw depth..................................................... 23
5.1.4.2 Borehole temperatures close to the study sites.......................................................................... 24
5.1.4.3 Thermal modelling .................................................................................................................... 25
5.2 Hydraulic properties........................................................................................................................... 27
5.2.1 Laminar and turbulent fluid flow in fractured rock....................................................................... 27
5.2.2 Influence of permafrost on permeability in fractured rock............................................................ 28
5.3 Mechanic properties............................................................................................................................ 29
5.3.1 Basic rock mechanical considerations........................................................................................... 29
5.3.1.1 Compressive and tensile strength of frozen and unfrozen rock................................................. 31
5.3.1.2 Total friction along a rough surface........................................................................................... 32
5.3.1.3 Brittle fracture propagation ....................................................................................................... 33
5.3.2 Basic ice mechanical considerations ............................................................................................. 34
5.3.2.1 Continuum behaviour................................................................................................................ 35
35.3.2.2 Fracture behaviour..................................................................................................................... 36
5.3.2.3 Failure in ice-filled rock fractures: empiric data ....................................................................... 37
5.3.2.4 A preliminary model for the failure of ice in rock clefts ........................................................... 38
5.3.3 A preliminary rock- and ice-mechanical model for rock instability in thawing permafrost rocks 39
5.3.3.1 Brittle fracture propagation of new sliding planes .................................................................... 39
5.3.3.2 Failure along existing sliding planes ......................................................................................... 40
5.3.4 Complexity factors: stress heterogeneity, hydrostatic pressure and dilatation by ice segregation 40
5.4 The geomorphic system ...................................................................................................................... 41
5.4.1 Equilibrium and non-equilibrium slopes....................................................................................... 41
5.4.2 The sensitivity concept.................................................................................................................. 42
5.4.2.1 Reaction time ............................................................................................................................ 43
5.4.2.2 Relaxation time ......................................................................................................................... 45
5.4.2.3 Disequilibrium and transience........