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| Titel |
Evaluation of seismic effects on the landslide deposits of Monte Salta (Eastern Italian Alps) using distinct element method |
| VerfasserIn |
G. Marcato, K. Fujisawa, M. Mantovani, A. Pasuto, S. Silvano, F. Tagliavini, L. Zabuski |
| 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 ; 7, no. 6 ; Nr. 7, no. 6 (2007-11-22), S.695-701 |
| Datensatznummer |
250004815
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| Publikation (Nr.) |
 copernicus.org/nhess-7-695-2007.pdf |
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| Zusammenfassung |
The aim of the paper is to present the modelling of the ground effects of
seismic waves on a large debris deposit lying on a steep mountain slope,
with particular attention paid to the potential triggering of slope
movements.
The study site is a mass of 2.5 million m3 rock fall deposit, named
"Monte Salta Landslide", located on the northern slope of the Vajont
valley, at the border between Veneto and Friuli Venezia Giulia regions in
north-eastern Italy.
Several historical landslide events were reported in the area in the past,
first one dating back to the 17th century. The landslide deposit completely
mantles the slope with a thick cover of rock blocks.
The Mt. Salta landslide is conditioned by the presence of Mt. Borgà
regional thrust, which uplifts Jurassic limestone on the top of Cretaceous
rock units. Above the thrust zone, folded and highly fractured rock mass
dips steeply towards the slope free face, producing highly unstable setting.
The study area has been classified as high seismic hazard and different
vulnerable elements can be affected by the remobilisation of debris, among
which a village, a national road and a big quarry that was opened, with the
intent to exploit the part of the landslide deposit for construction
purposes.
In this study, numerical analysis was performed, to simulate the slope
behaviour using distinct element method and applying UDEC code. The 2-D
models were built on three cross-sections and elasto-plastic behaviour was
assumed, both for rock matrix and discontinuities. The earthquake effect was
modelled in pseudo-dynamic way, i.e. by magnifying the acceleration and
applying also its horizontal component. The expected seismic acceleration in
the study area was calculated on the basis of previous studies as equal to
0.28 g.
The results proved that the increase of the vertical component alone has a
small influence on the deformational behaviour of the system. Hence, the
acceleration vector was deviated at 5° and then at 10° from the
vertical. A small increment of the displacement was observed in the first
case, whereas very large movements occurred in the second. Therefore, it can
be concluded that, besides the magnitude of the earthquake, even small
seismic waves in horizontal direction could trigger significant movements
and therefore hazardous conditions. The modelled scenario should be helpful
for planning of the functional countermeasure works and civil defence
evacuation plan. |
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