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| Titel |
Debris flow impact on mitigation barriers: a new method for particle-fluid-structure interactions |
| VerfasserIn |
Maddalena Marchelli, Marina Pirulli, Shiva P. Pudasaini |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250131332
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| Publikation (Nr.) |
 EGU/EGU2016-11730.pdf |
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| Zusammenfassung |
| Channelized debris-flows are a type of mass movements that involve water-charged,
predominantly coarse-grained inorganic and organic material flowing rapidly down steep
confined pre-existing channels (Van Dine, 1985). Due to their rapid movements and
destructive power, structural mitigation measures have become an integral part of counter
measures against these phenomena, to mitigate and prevent damages resulting from
debris-flow impact on urbanized areas. In particular, debris barriers and storage basins, with
some form of debris-straining structures incorporated into the barrier constructed across the
path of a debris-flow, have a dual role to play: (1) to stimulate deposition by presenting a
physical obstruction against flow, and (2) to guarantee that during normal conditions
stream water and bedload can pass through the structure; while, during and after an
extreme event, the water that is in the flow and some of the fine-grained sediment can
escape.
A new method to investigate the dynamic interactions between the flowing mass and the
debris barrier is presented, with particular emphasis on the effect of the barrier in controlling
the water and sediment content of the escaping mass. This aspect is achieved by
implementing a new mechanical model into an enhanced two-phase dynamical mass flow
model (Pudasaini, 2012), in which solid particles mixture and viscous fluid are
taken into account. The complex mechanical model is defined as a function of the
energy lost during impact, the physical and geometrical properties of the debris
barrier, separate but strongly interacting dynamics of boulder and fluid flows during
the impact, particle concentration distribution, and the slope characteristics. The
particle-filtering-process results in a large variation in the rheological properties of the
fluid-dominated escaping mass, including the substantial reduction in the bulk density,
and the inertial forces of the debris-flows. Consequently, the destructive power
and run-out are reduced, leading to positive effects on hazard assessments. The
validation of the new approach through numerical modeling of some laboratory
experiments and back-analysis of the flowing mass impacting against existing debris-flow
barriers located in some catchment basins in the Italian Alps will contribute in
understanding the comprehensive dynamic phenomenon and in the design of new control
barriers.
References:
Van Dine, D.F., 1985. Debris flows and debris torrents in the southern Canadian Cordillera.
Canadian Geotechnical Journal, 22: 44-68.
Pudasaini, S. P., 2012. A general two-phase debris flow model. Journal of Geophysical
Research, 117, F03010, doi: 10.1029/2011JF002186. |
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