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| Titel |
Evaluation of the rockfall susceptibility of the Solà D'Andorra using the Matterock methodology |
| VerfasserIn |
O. Mavrouli, A. Pedrazzini, A. Loye, M. Jaboyedoff, J. Corominas |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250044920
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| Zusammenfassung |
| The rockfall susceptibility of a slope is directly linked to the topographical relief and the
presence of favorable discontinuities for the detachment of rock volumes from
the slope face. In order to rank the rockfall susceptibility throughout a slope so
as to localize the zones which are the most probable to produce rockfalls, these
parameters have to be taken into consideration. In this context, the objective of this work
was the identification of susceptible areas on the Solà de Andorra, in Andorra.
The susceptibility is evaluated implementing a GIS platform and the Matterock
methodology (Rouiller et al., 1998) by superposition of four criteria that are related to the
topographical relief and the presence of discontinuities. The used parameters and the
related analyses to obtain them are the following and they are briefly described in the
continue:
1. Comparison of the slope angle with the threshold value defined by slope angle
analysis.
2. Average number of unfavorable discontinuities per surface unit.
3. Number of kinematically permitted plane or wedge failures.
4. Value in cubic meters of the potentially instable volumes using the Slope Local Base
Level, SLBL, method.
The slope angle analysis is used for the determination of an angle value above which
rockfalls are very probable. It is based on the decomposition of the histogram of the present
slope angles to different families, using a Gaussian distribution. The families represent the
existing geo-morphological structures. The threshold value is determined by the angle
characterizing the steepest family.
The unfavorable discontinuities are detected using the Matterock software. The input data
is the DEM and the principal discontinuity sets. The output is the average number of
discontinuities counted in every topographic facet.
The kinematic tests are also performed using the Matterock software. For each
unfavorable discontinuity set, the number of potential plane or wedge failures is
calculated.
The volumes above a base level that is determined by the topographical relief are
calculated using the SLBL method, also on a GIS platform.
For the application at a local scale to the Solà de Andorra, the four analyses are
performed and their outputs are ranked using appropriate rating. The susceptibility index that
is used is equal to the sum of the ranked outputs and it is expressed on an increasing scale
from 0 to 8. Historical rockfall events are superimposed on the topographic map to check the
consistency of the results. It is indicated that areas characterized by high values of the
susceptibility index coincide with past events, thus may be considered prone to also produce
rockfalls in the future.
References
Rouiller, J.-D., Jaboyedoff, M., Marro, C., Phlippossian, F. and Mamin, M.
(1998): Pentes instables dans le Pennique valaisan. Rapport final PNR31. VDF,
Zürich. |
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