PosterDjamil Al-Halbouni, Eoghan P. Holohan, Abbas Taheri, and Torsten Dah

Al-Halbouni, D.

Dahm, T.

Holohan, E.

Taheri, A.

Adelaide Research &amp; Scholarship

PUBLISHED VERSION  Djamil Al-Halbouni, Eoghan P. Holohan, Abbas Taheri, and Torsten Dahm Distinct element modeling of geophysical signatures during sinkhole collapse Geophysical Research Abstracts, 2017 / pp.1   © Authors 2017. CC attribution 3.0 License                                http://hdl.handle.net/2440/106685  PERMISSIONS http://creativecommons.org/licenses/by/3.0/     11 August, 2017 Geophysical Research AbstractsVol. 19, EGU2017-922-1, 2017EGU General Assembly 2017© Author(s) 2017. CC Attribution 3.0 License.Distinct Element modeling of geophysical signatures during sinkholecollapseDjamil Al-Halbouni (1), Eoghan P. Holohan (2), Abbas Taheri (3), and Torsten Dahm (1)(1) GFZ German Research Center for Geosciences, Physics of the Earth, Potsdam, Germany (halbouni@gfz-potsdam.de), (2)UCD School of Earth Sciences, University College Dublin, Belfield, Dublin 4, Ireland., (3) School of Civil, Environmentaland Mining Engineering, The University of Adelaide, AustraliaA sinkhole forms due to the collapse of rocks or soil near the Earth’s surface into an underground cavity. Suchcavities represent large secondary pore spaces derived by dissolution and subrosion in the underground. Bychanging the stress field in the surrounding material, the growth of cavities can lead to a positive feedback, inwhich expansion and mechanical instability in the surrounding material increases or generates new secondarypore space (e.g. by fracturing), which in turn increases the cavity size, etc. A sinkhole forms due to the eventualsubsidence or collapse of the overburden that becomes destabilized and fails all the way to the Earth’s surface.Both natural processes like (sub)surface water movement and earthquakes, and human activities, such as mining,construction and groundwater extraction, intensify such feedbacks. The development of models for the mechanicalinteraction of a growing cavity and fracturing of its surrounding material, thus capturing related precursorygeophysical signatures, has been limited, however.Here we report on the advances of a general, simplified approach to simulating cavity growth and sinkholeformation by using 2D Distinct Element Modeling (DEM) PFC5.0 software and thereby constraining pre-, syn-and post-collapse geophysical and geodetic signatures. This physically realistic approach allows for spontaneouscavity development and dislocation of rock mass to be simulated by bonded particle formulation of DEM.First, we present calibration and validation of our model. Surface subsidence above an instantaneously ex-cavated circular cavity is tracked and compared with an incrementally increasing dissolution zone both for purelyelastic and non-elastic material.This validation is important for the optimal choice of model dimensions andparticles size with respect to simulation time.Second, a cavity growth approach is presented and compared to a well-documented case study, the deliber-ately intensified sinkhole collapse at Cerville-Buissoncourt in France. The outcomes of our model are comparedwith available extensiometer, surface-subsidence and microseismicity measurements during the pre- and syn-collapse period.The proposed model development and a possible archive of modeled scenarios may, in combination with ageodetic and seismological sinkhole monitoring, contribute to an early-warning tool for end-users and decisionmakers in areas affected by natural (e.g. Dead Sea) or man-made sinkhole collapses (mines).

Distinct element modeling of geophysical signatures during sinkhole collapse

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