Predicting of land surface uplift caused by the flooding of underground coal mines – A case study

• Published in: International journal of rock mechanics and mining sciences (Oxford, England : 1997) England : 1997), 2020-08, Vol.132, p.104377, Article 104377
• Main Authors: Dudek, Mateusz, Tajduś, Krzysztof, Misa, Rafał, Sroka, Anton
• Format: Article
• Language: English
• Subjects: Analytical methods; Chemical pollution; Coal mines; Coal mining; Environmental changes; Finite element method; Flood predictions; Flooding; Floods; Forecasting; Hydrologic data; Mathematical models; Mechanical properties; Mine flooding; Mines; Mining closure; Numerical methods; Numerical modeling; Numerical models; Physical properties; Prediction; Rock masses; Rock mechanics; Rock properties; Rocks; Soil mechanics; Strain; Surface uplift; Surface water; Three dimensional models; Underground mines; Uplift; Water pollution; Water table
• ISSN: 1365-1609; 1873-4545
• DOI: 10.1016/j.ijrmms.2020.104377

The liquidation of underground mines as in flooding of mining excavations and goafs often leads to movements of the rock mass and land surface as a result of pressure changes in the flooded zones. The changes resulting from the rising water table caused by the changes in the stress and strain state as well as the physical and mechanical properties of rock layers can lead to damage to surface construction objects and environmental changes, such as chemical pollution of the surface water. This is why the ability to predict the movements of rock masses generated as a result of mine closure by flooding serves a key function in relation to the protection of the land surface and buildings present thereon. Currently, the world literature presenting methods of forecasting ground surface uplift during mine flooding is very modest and is limited to three analytical methods: Pöttgens', Fenk's and Sroka's method. However, the numerical methods used in this subject area are limited only to modeling the phenomenon using the back analysis method and are not used for forecasting. The author's methodology based on the finite element method presented in the article allows on, after calibrating the 3D numerical model using surface subsidence measurements, as well as geological and mining data, to simulate the flooding process by changing the density of the medium according to classical soil and rock mechanics principles and then obtain prognostic values for ground surface uplift. This methodology has been used in the example of a German underground coal mine, which has been flooded in 1999. The authors have built a 3D numerical model and then performed simulations. The results of calculations were compared with the results of measurements obtaining compliance at the level of 5%. •Europe's energy policy has forced many mines to close.•The mine flooding impact on the rock mass has not been sufficiently studied.•The effect of mine flooding is most often observed as continuous deformation.•Land surface deformation in form of uplift can be predict using FEM analyses.•Predicting methodology has been presented and verified on a case study.