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Number of results: 8
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Abstract

The theory of Professor Stanislaw Knothe, known as Knothe’s Theory, has been the foundation for practical predictive calculations of the impacts of exploitation for many years. It has enabled the large-scale extraction of coal, salt and metal ores located in the protective pillars of cities and prime surface structures. Knothe’s Theory has been successfully applied in Polish and global mining for over seventy years, making it one of the most well-known and recognized achievements in Polish mining science. Knothe’s Theory provides a temporal-spatial description of subsidence that relies on four essential parameters: the vertical scale parameter a, the horizontal displacement parameter λ, the horizontal range scale parameter cotβ and the time scale parameter c.
This article characterizes the parameters of Knothe’s Theory used in various current applications for calculating subsidence, surface and rock uplift, and other applications of the theory, even beyond its classical form. The presented solutions are based on a mathematical model of the interaction of a complex element and cover topics such as subsidence during full exploitation with roof collapse and full exploitation with backfilling, pillar-room mining, the effect of salt caverns on the surface and salt rock, and fluid deposits and surface uplift caused by changes in the water level within closed coal mines. The article also discusses the evolution of the range angle of the main influences and presents Knothe’s solutions related to time, describing the horizontal displacement parameter λ.
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Authors and Affiliations

Rafał Misa
1
ORCID: ORCID

  1. Strata Mechanics Research Institute, Polish Academy of Science, Kraków, Poland
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Abstract

The paper presents a new geotechnical solution indicating a possibility of effective building structures protection. The presented solutions enable minimization of negative effects of underground mining operations. Results of numerical modelling have been presented for an example of design of preventive ditches reducing the influence of mining operations on the ground surface. To minimize the mining damage or to reduce its reach it is reasonable to look for technical solutions, which would enable effective protection of building structures. So far authors concentrated primarily on the development of building structure protection methods to minimize the damage caused by the underground mining. The application of geotechnical methods, which could protect building structures against the mining damage, was not considered so far in scientific papers. It should be noticed that relatively few publications are directly related to those issues and there are no practical examples of effective geotechnical protection. This paper presents a geotechnical solution indicating a possibility of effective protection of building structures. The presented solutions enable minimization of negative effects of underground mining operations. Results of numerical modelling have been presented for an example of design of preventive ditches reducing the influence of mining operations on the ground surface. The calculations were carried out in the Abaqus software, based on the finite element method.

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Authors and Affiliations

Rafał Misa
ORCID: ORCID
Krzysztof Tajduś
ORCID: ORCID
Anton Sroka
ORCID: ORCID
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Abstract

Coal is the main energy source in China, but its underground mining causes surface subsidence, which seriously damages the ecological and living environments. How to calculate subsidence accurately is a core issue in evaluating mining damage. At present, the most commonly used method of calculation is the Probability Integral Method (PIM), based on a normal distribution. However, this method has limitations in thick topsoil (thickness > 100 m), in that the extent of the calculated boundary of the subsidence basin is smaller than its real extent, and this has an undoubted impact on the accurate assessment of the extent of mining damage. Therefore, this paper introduces a calculation model for surface subsidence based on a Cauchy distribution for thick topsoil conditions. This not only improves the accuracy of calculation at the subsidence basin boundary, but also provides a universal method for the calculation of surface subsidence.

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Authors and Affiliations

Yue Jiang
Rafał Misa
ORCID: ORCID
Krzysztof Tajduś
ORCID: ORCID
Anton Sroka
ORCID: ORCID
Yan Jiang
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Abstract

The article presents a methodology for determining the value of the expansion coefficient of a reconsolidated caving zone in the context of forecasting the rise in underground mine water levels and consequent surface subsidence caused by the process of flooding the closed coal mines. The paper also provides a brief characterisation of analytical predictive models regarding surface subsidence during the process of flooding coal mines. In order to describe the vertical deformation of the reconsolidated porous rock mass in the caving zone, a linear-elastic medium of Biot was utilised. The conducted theoretical calculations demonstrate a high agreement with the results obtained through the identification of the expansion coefficient parameter based on the analysis of in-situ subsidence measurements in Dutch and German mining areas. The proposed methodology was applied to a real case study involving the forecasting of the impact of the flooding process on the underground workings of the German Ibbenbüren mine. The article constitutes a significant contribution to the field of forecasting the rise in underground mine water levels and surface subsidence during the process of flooding closed coal mines. The presented methodology and obtained results can be valuable for researchers, engineers, and decision-makers involved in the planning and management of mining areas.
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Authors and Affiliations

Rafał Misa
1
ORCID: ORCID
Mateusz Dudek
1
ORCID: ORCID
Anton Sroka
1
ORCID: ORCID
Krzysztof Tajduś
2
ORCID: ORCID
Dawid Mrocheń
1
ORCID: ORCID

  1. Strata Mechanics Research Institute, Polish Academy of Science, Krakow, Poland
  2. AGH University of Science and Technology, Krakow, Poland
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Abstract

This paper presents one of the environmental problems occurring during underground mine closures: according to the underground coal mine closure programme in Germany, the behaviour of the land surface caused by flooding of the entire planned mining area – the Ruhr District – had to be addressed. It was highlighted that water drainage would need to be continuous; otherwise, water levels would rise again in the mining areas, resulting in flooding of currently highly urbanised zones. Based on the variant analysis, it was concluded that the expected uniform ground movements caused by the planned rise in the mining water levels (comprising a part of two concepts – flooding up to the level of –500 m a.s.l. and −600 m a.s.l.), in the RAG Aktiengesellschaft mines, will not result in new mining damage to traditional buildings. The analysis included calculations of the maximum land surface uplift and the most unfavourable deformation factor values on the land surface, important from the point of view of buildings and structures: tilt T, compressive strain ε– and tensile strain ε+. The impact of flooding on potential, discontinuous land surface deformation was also analysed.
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Authors and Affiliations

Krzysztof Tajduś
1
ORCID: ORCID
Anton Sroka
2
ORCID: ORCID
Mateusz Dudek
2
ORCID: ORCID
Rafał Misa
2
ORCID: ORCID
Stefan Hager
3
ORCID: ORCID
Janusz Rusek
1
ORCID: ORCID

  1. AGH University of Krakow, Al. A. Mickiewicza 30, 30-059 Kraków, Poland
  2. Strata Mechanics Research Institutes of Polish Academy of Science, 27 Reymonta Str., 30-059 Kraków, Poland
  3. R AG Aktiengesellschaft, Essen, Germany
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Abstract

The article presents three German-located case studies based on stochastic methods founded by the theory proposed by Knothe and the development of the ‘Ruhrkohle method’ according to Ehrhardt and Sauer. These solutions are successfully applied to predict mining-induced ground movements. The possibility of forecasting both vertical and horizontal ground movements has been presented in the manuscript, which allowed for optimization mining projects in terms of predicted ground movements.
The first example presents the extraction of the Mausegatt seam beneath the district of Moers-Kapellen in the Niederberg mine. Considering, among others, the adaption of the dynamic impact of the underground operations to the mining-induced sensitivity of surface objects, the maximum permissible rate of the face advance has been determined.
The second example presents the extraction of coal panel 479 in the Johann seam located directly in the fissure zone of Recklinghausen-North. Also, in this case, the protection of motorway bridge structure (BAB A43/L225) to mining influences has been presented. The Ruhrkohle method was used as a basis for the mathematical model that was developed to calculate the maximum horizontal opening of the fissure zone and the maximum gap development rate.
Part of the article is dedicated to ground uplift due to rising mine water levels. Although it is not the main factor causing mining-related damage, such movements in the rock masses should also be predicted. As the example of the Königsborn mine, liquidated by flooding, shows stochastic processes are well suited for predicting ground uplift. The only condition is the introduction of minor adjustments in the model and the use of appropriate parameters.
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Authors and Affiliations

Anton Sroka
1
ORCID: ORCID
Stefan Hager
2
ORCID: ORCID
Rafał Misa
1
ORCID: ORCID
Krzysztof Tajduś
1
ORCID: ORCID
Mateusz Dudek
1
ORCID: ORCID

  1. Strata Mechanics Research Institute, Polish Academy of Science, Kraków, Poland
  2. RAG Aktiengesellschaft, Im Welterbe 10, 45141 Essen, Germany

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