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| Titel |
Subsidence and collapse sinkholes in soluble rock: a numerical perspective |
| VerfasserIn |
Georg Kaufmann, Douchko Romanov, Thomas Hiller |
| 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 |
250126028
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| Publikation (Nr.) |
 EGU/EGU2016-5699.pdf |
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| Zusammenfassung |
| Soluble rocks such as limestone, gypsum, anhydrite, and salt are prone to subsidence and the
sudden creation of collapse sinkholes. The reason for this behaviour stems from the solubility
of the rock: Water percolating through fissures and bedding partings can remove material
from the rock walls and thus increase the permeability of the host rock by orders of
magnitudes. This process occurs on time scales of 1,000-100,000 years, resulting in
enlarged fractures, voids and cavities, which then carry flow efficiently through the
rock.
The enlargement of sub-surface voids to the meter-size within such short times creates
mechanical conditions prone to collapse. The collapse initiates at depth, but then propagates
to the surface.
By means of numerical modelling, we discuss the long-term evolution of secondary
porosity in gypsum rocks, resulting in zones of sub-surface voids, which then become
mechanically unstable and collapse. We study two real-world case scenarios, in which we can
relate field observations to our numerical model: (i) A dam-site scenario, where flow around
the dam caused widespread dissolution of gypsum and subsequent subsidence of the dam and
a nearby highway. (ii) A natural collapse sinkhole forming as a result of freshwater inflow
into a shallow anhydrite formation with rapid evolution of voids in the sub-surface. |
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