Geomechanical modelling of sinkhole development using distinct elements: model verification for a single void space and application to the Dead Sea area

Abstract

Abstract. 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.

An Innovative Method for Placement of Gangue Backfilling Material in Steep Underground Coal Mines

“…The Particle Flow Code (PFC) has been used widely in geotechnical engineering to simulate geomaterials [36,37]. In this study, PFC2D 3.10 (Itasca Consulting Group, Inc., Minneapolis, MN, USA) was used to study the movement of the gangue in the goaf after mining with flexible shield supports of a steep coal seam and to analyze the influence of the inclined length and arrangement of the working face.…”

A Review of Underground Pipeline Leakage and Sinkhole Monitoring Methods Based on Wireless Sensor Networking

“…Researchers considered sea side soil (mudflat, sea clay) as a soil type, and subsurface void growth, ground water level, salt dissolution, and overburden pressure as the factors responsible for sinkhole or subsidence in their experiments [119,120] as the researchers aimed to understand the mechanism of sinkhole along the seaside. Therefore, this sinkhole mechanism cannot be true for other cases, as other soil types need to be considered (clay, sand, bedrock, carbonates, etc.)…”

A reactivated cave system induces rapidly developing cover-collapse sinkholes in Tasmania, Australia

“…Eventually a void may become so big that the roof of the void cannot support itself and the ground surface suddenly collapses into a vertical or steep-walled sinkhole (Cooley, 2002). Overburden composed of layers of varying mechanical strength is particularly susceptible to collapse (Al-Halbouni et al, 2018). Laboratory simulations of this process have been detailed by Soliman et al (2018).…”