Geomechanical modelling of sinkhole development using distinct elements: model verification for a single void space and application to the Dead Sea area
<p>Mechanical and/or chemical removal of material from the subsurface may generate large subsurface cavities, the destabilisation of which can lead to ground collapse and the formation of sinkholes. Numerical simulation of the interaction of cavity growth, host material deformation and ove...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-11-01
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| Series: | Solid Earth |
| Online Access: | https://www.solid-earth.net/9/1341/2018/se-9-1341-2018.pdf |
| Summary: | <p>Mechanical and/or chemical removal of material from the
subsurface may generate large subsurface cavities, the destabilisation of
which can lead to ground collapse and the formation of sinkholes. Numerical
simulation of the interaction of cavity growth, host material deformation
and overburden collapse is desirable to better understand the sinkhole
hazard but is a challenging task due to the involved high strains and
material discontinuities. Here, we present 2-D distinct element method
numerical simulations of cavity growth and sinkhole development. Firstly, we
simulate cavity formation by quasi-static, stepwise removal of material in
a single growing zone of an arbitrary geometry and depth. We benchmark this
approach against analytical and boundary element method models of a deep
void space in a linear elastic material. Secondly, we explore the effects of
properties of different uniform materials on cavity stability and sinkhole
development. We perform simulated biaxial tests to calibrate macroscopic
geotechnical parameters of three model materials representative of those in
which sinkholes develop at the Dead Sea shoreline: mud, alluvium and salt.
We show that weak materials do not support large cavities, leading to
gradual sagging or suffusion-style subsidence. Strong materials support
quasi-stable to stable cavities, the overburdens of which may fail suddenly
in a caprock or bedrock collapse style. Thirdly, we examine the consequences
of layered arrangements of weak and strong materials. We find that these are
more susceptible to sinkhole collapse than uniform materials not only due to
a lower integrated strength of the overburden but also due to an inhibition
of stabilising stress arching. Finally, we compare our model sinkhole
geometries to observations at the Ghor Al-Haditha sinkhole site in Jordan.
Sinkhole depth ∕ diameter ratios of 0.15 in mud, 0.37 in alluvium and 0.33
in salt are reproduced successfully in the calibrated model materials. The
model results suggest that the observed distribution of sinkhole
depth ∕ diameter values in each material type may partly reflect sinkhole
growth trends.</p> |
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| ISSN: | 1869-9510 1869-9529 |