Titel
Distinct element geomechanical modelling of the formation of sinkhole clusters within large-scale karstic depressions
Autor*in
Djamil Al-Halbouni
Helmholtz Centre – German Research Centre for Geosciences (GFZ), Physics of Earthquakes and Volcanoes
Autor*in
Eoghan P. Holohan
UCD School of Earth Sciences, University College Dublin
Autor*in
Abbas Taheri
School of Civil, Environmental and Mining Engineering, University of Adelaide
... show all
Abstract
The 2-D distinct element method (DEM) code (PFC2D_V5) is used here to simulate the evolution of subsidence-related karst landforms, such as single and clustered sinkholes, and associated larger-scale depressions. Subsurface material in the DEM model is removed progressively to produce an array of cavities; this simulates a network of subsurface groundwater conduits growing by chemical/mechanical erosion. The growth of the cavity array is coupled mechanically to the gravitationally loaded surroundings, such that cavities can grow also in part by material failure at their margins, which in the limit can produce individual collapse sinkholes. Two end-member growth scenarios of the cavity array and their impact on surface subsidence were examined in the models: (1) cavity growth at the same depth level and growth rate; (2) cavity growth at progressively deepening levels with varying growth rates. These growth scenarios are characterised by differing stress patterns across the cavity array and its overburden, which are in turn an important factor for the formation of sinkholes and uvala-like depressions. For growth scenario (1), a stable compression arch is established around the entire cavity array, hindering sinkhole collapse into individual cavities and favouring block-wise, relatively even subsidence across the whole cavity array. In contrast, for growth scenario (2), the stress system is more heterogeneous, such that local stress concentrations exist around individual cavities, leading to stress interactions and local wall/overburden fractures. Consequently, sinkhole collapses occur in individual cavities, which results in uneven, differential subsidence within a larger-scale depression. Depending on material properties of the cavity-hosting material and the overburden, the larger-scale depression forms either by sinkhole coalescence or by widespread subsidence linked geometrically to the entire cavity array. The results from models with growth scenario (2) are in close agreement with surface morphological and subsurface geophysical observations from an evaporite karst area on the eastern shore of the Dead Sea.
Stichwort
Earth-Surface ProcessesStratigraphyPalaeontologySoil ScienceGeologyGeochemistry and PetrologyGeophysics
Objekt-Typ
Sprache
Englisch [eng]
Persistent identifier
https://phaidra.univie.ac.at/o:1177629
Erschienen in
Titel
Solid Earth
Band
10
Ausgabe
4
ISSN
1869-9529
Erscheinungsdatum
2019
Seitenanfang
1219
Seitenende
1241
Verlag
Copernicus GmbH
Projektnummer
03G0843 – Federal Ministry of Education and Research of Germany
Projektnummer
VH-VI-527 – Helmholtz DESERVE Virtual Institute
Erscheinungsdatum
2019
Zugänglichkeit
Rechteangabe
© Author(s) 2019

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