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| Titel |
Influence of weathering and pre-existing large scale fractures on gravitational slope failure: insights from 3-D physical modelling |
| VerfasserIn |
D. Bachmann, S. Bouissou, A. Chemenda |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 4, no. 5/6 ; Nr. 4, no. 5/6 (2004-11-17), S.711-717 |
| Datensatznummer |
250001389
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| Publikation (Nr.) |
 copernicus.org/nhess-4-711-2004.pdf |
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| Zusammenfassung |
| Using a new 3-D physical modelling technique we investigated the initiation
and evolution of large scale landslides in presence of pre-existing large
scale fractures and taking into account the slope material weakening due to
the alteration/weathering. The modelling technique is based on the specially
developed properly scaled analogue materials, as well as on the original
vertical accelerator device enabling increases in the "gravity
acceleration" up to a factor 50. The weathering primarily affects the
uppermost layers through the water circulation. We simulated the effect of
this process by making models of two parts. The shallower one represents the
zone subject to homogeneous weathering and is made of low strength material
of compressive strength σl. The deeper (core) part of the model
is stronger and simulates intact rocks. Deformation of such a model
subjected to the gravity force occurred only in its upper (low strength)
layer. In another set of experiments, low strength (σw) narrow
planar zones sub-parallel to the slope surface (σw<σl) were introduced into the model's superficial low strength layer to
simulate localized highly weathered zones. In this configuration landslides
were initiated much easier (at lower "gravity force"), were shallower and
had smaller horizontal size largely defined by the weak zone size.
Pre-existing fractures were introduced into the model by cutting it along a
given plan. They have proved to be of small influence on the slope
stability, except when they were associated to highly weathered zones. In
this latter case the fractures laterally limited the slides. Deep seated
rockslides initiation is thus directly defined by the mechanical structure
of the hillslope's uppermost levels and especially by the presence of the
weak zones due to the weathering. The large scale fractures play a more
passive role and can only influence the shape and the volume of the sliding
units. |
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