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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. [ABSTRACT FROM AUTHOR]

Spatio-temporal ground-movement measurements and mappings have been carried out in the Campine coalfield in Belgian Limburg since the closure of the mines to document post-mining effects. MT-InSAR measurements are compared to groundwater head changes in the overburden and to height data from the closest GNSS stations. Radar interferometry is used to estimate the extension and the velocity of ground movements. In particular, the MT-InSAR technique has been applied to SAR acquisitions of the satellites ERS-1/2 (1991–2005), ENVISAT (2003–2010), COSMO-SkyMed (2011–2014), and Sentinel-1A (2014–2022). The images were processed and used to highlight a switch from subsidence to uplift conditions in the western part of the coal basin, while the eastern part had already been affected by a rebound since the beginning of the ERS-1/2 acquisitions. Following the closure of the last active colliery of Zolder in 1992 and the subsequent cease of mine-water pumping, a recharge of mine-water aquifers occurred in the western part of the basin. This process provoked the change from subsidence to uplift conditions that was recorded during the ENVISAT period. In the center of the coal-mining area, measured uplift velocities reached a maximum of 18 mm/year during the ENVISAT period, while they subsided at −12 mm/year during the ERS-1/2 period. Mean velocities in the western and eastern parts of the coalfield area have decreased since the last MT-InSAR measurements were performed using Sentinel-1A, while the Zolder coal mine continues to rise at a faster-than-average rate of a maximum of 16 mm/year. The eastern part of the coalfield is still uplifting, while its rate has been reduced from 18 mm/year (ERS-1/2) to 9 mm/year (Sentinel-1A) since the beginning of the radar–satellite observations. Time-series data from the two GNSS stations present in the study area were used for a local comparison with the evolution of ground movements observed by MT-InSAR. Two leveling campaigns (2000, 2013) were also used to make comparisons with the MT-InSAR data. The station's measurements and the leveling data were in line with the MT-InSAR data. Overall, major ground movements are obviously limited to an extension of the actual underground-mining works and rapidly diminish outside of them. [ABSTRACT FROM AUTHOR]

The end of hard coal mining in Germany and other European countries has been leading to new challenges in post-mining and utilisation of abandoned mines while opening up new perspectives concerning the remains of former mining as well as new fields of work for specialised personnel at the same time. Coping with the resulting perpetual tasks places new demands on already trained experts and offers the opportunity to familiarise the next generation of students with post-mining issues and solution approaches from the beginning. This article presents two closely interrelated projects – the USAMIN Project and the PepperMINT Project – which aim to successfully recruit and train future professionals. For this purpose, the USAMIN (USe of Abandoned MINes) Project creates a new form of distance learning as multilateral cooperation, which strengthens the training of specialised experts and the scientific exchange across European borders. Furthermore, the main goal of this project is the establishment of networks between scientists and other experts, thus strengthening international cooperation. The PepperMINT Project’s STEM online courses aim to motivate high school students to pursue STEM studies by introducing them to the field of engineering, while simultaneously strengthening students, especially in their first semesters. By linking the two projects, various actors can be connected according to their education and a large part of the education chain can be viewed in a holistic approach. [ABSTRACT FROM AUTHOR]

The Ruhr Basin in Germany is one of the most extensively studied 3D rock volumes due to subsurface coal mining over the past centuries. With the final closure of the last coalfield in 2018, mine flooding was initiated and may result in induced ground movements. However, abandoned coal mines also provide the possibility for post-mining geothermal utilisation. To improve the understanding of rock properties with respect to flow properties and heat flux in the Ruhr Basin, three drill cores of clastic sedimentary rocks of the Westphalian A (Langsettian) and Westphalian B (Duckmantian) were characterised and the facies analysed. The studied 270 m core material show 4th order sequences of coarsening- and fining-upward cycles in an overall shallowing upward trend. Up to 17 m thick sandstone beds are associated with the delta front, mudstones and siltstones are related to the lower delta plain and up to 4 m thick coal seams linked to wetlands of the lower delta plain. Rock properties show low compressional velocities with a minimum of 2,886 m/s in sandstones of the delta front, which are negatively correlated with porosities of up to 15.6%. Likewise, porosity is a major control on thermal conductivity with a minimum of 2.3 W/(m×K) for high porosity sandstones. For less porous samples, thermal conductivity becomes less dependent on porosity but more strongly on mineralogy. Comparing our results with accessible thermal conductivity data from North Rhine-Westphalia (NRW), the high values of up to 5.3 W/(m×K) seem promising for potential geothermal applications. Furthermore, the results of this study imply that the classification based on facies associations is less suitable than the classification based on grain sizes in order to assess the geothermal potential. Overall, the Upper Carboniferous (Pennsylvanian) samples of this study show low porosity (mean 5.6%) and permeability (mean 0.1 mD). Thus fluid flow during mine flooding and potential future geothermal applications will primarily rely on permeable faults and fracture systems around the abandoned mine galleries as well as the galleries themselves. [ABSTRACT FROM AUTHOR]

As part of the FloodRisk project, the influence of rising mine water in abandoned coal mines on induced seismicity is investigated. The Seismological Observatory of the Ruhr University Bochum operates a monitoring network for the whole Ruhr area (North Rhine-Westphalia, Germany) since 1983. The local scale FloodRisk network was installed in the eastern part of the Ruhr area in 2020. The continuous monitoring opens up the opportunity for a long-term study of seismicity in combination with water levels related to mining in the region. The resulting database for the eastern Ruhr area includes over 13,000 induced earthquakes in a period of 26 years during active mining, very few events in the postmining phase before the onset of flooding and more than 1,700 events in the first two and a half years of flooding. The seismological database is supplemented by the mine water levels, which are regularly measured at various measuring points distributed over the study dewatering area “Haus Aden” and made available by Ruhrkohle Aktiengesellschaft (RAG). Seismic activity was highest in the phase of active mining and concentrated in the vicinity of the mining areas. After the end of mining, only very low seismicity was detected. With the start of flooding, significantly more events were registered again. The rise curve of the mine water level and the temporal and spatial distribution of the seismicity are observed and analysed. Five temporal flooding phases are identified in which the correlated seismicity shows different distribution patterns. Phases in which the levels of individual sections of the mine merge in flooding show particularly high seismicity. A strong spatial clustering of well-localised events occurs below the deepest flooded levels of the mine. Several mechanisms that alter the stress in active mining and flooded mines and induce seismic events are known from previous studies. To apply this to our study, particular attention is given to the spatial distribution of seismicity in relation to known geologic and mining structures. In the flooding phase, most of the seismicity is localised in the area below the flooded drifts. [ABSTRACT FROM AUTHOR]

Mining of hard coal creates large underground cavities, which significantly affect the subsurface and land surface. Observations of land surface behaviour after the closure of mines demonstrate that these threats do not disappear. During mine water rebound in the post-mining phase of underground coalmines, the water flows into the open mine workings and other altered or fissured areas. This paper provides early observations from the PostMinQuake project, which is designed to identify mechanisms, relevant parameters and dependencies of mining and geological parameters causing post-mining seismicity in several European coal regions. It also presents the correlation between seismicity and water table level in the studied basins that has been observed during the post-mining phase and shows the necessity of implementing new procedures to monitor these seismic events. [ABSTRACT FROM AUTHOR]

The successive end of hard coal mining, which took place in the various coalfields in Germany by 2018, poses the risk of possible future mining damage related to mine water rise after mine closure. In this study, an interdisciplinary approach of structural geological and geochemical methods was applied to detect active fault zones, as a first step for long-term monitoring of mine flooding. The geomechanical analysis in the area of the soil gas campaign at the former coal mine “Haus Aden” shows high dilation and moderate slip tendencies as well as the potential for critical stress of the selected fault section of the Königsborn Fault. These features indicate the section under consideration as a preferred gas migration pathway. Soil gas measurements showed correspondingly clear anomalies of the components CO2, 222Rn and O2, which together with the results of the geomechanical analysis are a strong indicator for a structurally controlled migration of the gases and thus evidence of the modelled fault outcrop. A possible accompanying fault could not be identified properly, mainly because of the ambiguous CO2 concentrations. A positive correlation of CO2 and 222Rn can be a supplementary statistical tool to better assign unclear gas anomalies. However, this approach is limited by the radioactive decay of 222Rn and individual site parameters (groundwater, gas permeabilities). The primary mine gas CH4 could not be detected, which is probably related to its oxidative decomposition with formation of CO2. In the next step, it is planned to validate the current results with area-wide measurements if possible and then to expand selected boreholes to gas gauges. Newly developed, permanent gas sensors will be installed into these gas gauges for long-term monitoring of mine flooding. The aim is to provide new low-cost options for flooding monitoring in order to be able to estimate induced seismicity and mine damage. [ABSTRACT FROM AUTHOR]

In the coal phase-out era, achieving sustainable mine closure is significant and prioritizes targets for the mining industry. In this study, the already closed lignite mine of Kardia, North Greece, is investigated, where the mine void left is naturally filled with water. The viability of different repurposing land uses is evaluated, and the natural water level development inside the mine pit is investigated concerning its future uses. The potential for solar photovoltaic (PV) panels developed on mining land and its surrounding area is evaluated in combination with the application of pumped hydro storage (PHS) technology, utilizing pit lake water. Except for electricity system planning, other end-uses that offer multiple, mutually reinforcing and lasting benefits are investigated, such as recreation parks, terrestrial wildlife, aquaculture and agriculture. All repurposing scenarios are evaluated with regard to the spatiotemporal evolution of the lake, by generating forecasts of the dependent variables (rainfall and temperature) via linear (autoregressive integrated moving average) and non-linear (artificial neural network) models. The prediction of pit lake natural development redefines the new land use layout and the land repurposing decisions. This is essential for strategic planning, considering the Greek lignite mining industry's priority regarding transitioning from the current coal-based electricity to renewable energy sources (RES) technology. [ABSTRACT FROM AUTHOR]

Recent changes in the fossil-fuel energy sector require coal mining industries to plan for the future, including developing procedures for decommissioning and closure associated with mines. In surface coal mining, the geotechnical issues of decommissioning include the long-term stability of the pit slopes, particularly as the pit is gradually filled with water. This paper investigates such slope stability issues, with emphasis on the conditions prevailing in the Amyntaion surface lignite mine, in Western Macedonia, Greece. Analytical and numerical methods have been developed and used to estimate the temporal evolution of the overall safety factor, as the water level in the pit rises, creating a lake. It is shown that until the water level in the lake reaches a critical depth of approximately 15–35% of the final equilibrium condition, the safety factor against the overall slope instability decreases slightly (by about 3% in the case study, and up to 5–10% in other conditions) compared to its value at the end of exploitation. At higher lake levels, the safety factor increases significantly, as the beneficial effect of the lake water pressure acting on the slope overcomes the adverse effect of pore water pressure rise inside the slope. In typical mines, the critical water depth is achieved within a few years, since the surface area of the pit is smaller at deeper levels; thus, more favorable slope stability conditions are usually reinstated a few years after mine closure, while the small reduction in safety during the initial stages after closure is inconsequential. The paper investigates the parameters influencing the magnitude of the small reduction in the short-term safety factor and produces normalized graphs of the evolution of the safety factor as the lake water level rises. The results of the analyses can be used in preliminary closure studies of surface coal mines. [ABSTRACT FROM AUTHOR]

In the context of a groundswell of interest in developing innovative post-mining landscapes, this paper explores post-mining imaginaries through the example of a recently closed coal mine, Leigh Creek in South Australia. We explore how these imaginaries are put forward by the mine's local communities, multiple levels of government and the mining company itself. In this case, as occurs more broadly in coal mining, these imaginaries are co-constructed by the ever-present risk of underground spontaneous combustion—spon-com—as a result of mining practices. This article addresses the role of spon-com as not only a physical phenomenon of the underground, but as a socio-environmental mechanism wielding considerable political power in relation to post-mining possibilities. We contribute to the geopolitical discourse on the 'subterranean turn' by drawing on concepts of haunting-as-circumstance to explore the political agency of the underground to reach above and manipulate surface politics. We thereby complicate Maria de Lourdes Melo Zurita's identification of a pre-existing sub terra nullius that positions the subsurface as political nothingness awaiting human intervention. This is a crucial step forward in thinking through concepts informing understandings of surface–subsurface relations, including the introduction of spectral thinking within subterranean geopolitics. We thus advance scholarship on subterranean geographies by progressing concepts of inhuman agency grounded in a situated example of this agency in practice. [ABSTRACT FROM AUTHOR]

Underground and opencast mining adversely affects the surrounding environment. This process may continue even decades after the end of actual mineral extraction. One of the most significant effects of ceased mining are secondary deformations. Safe, new development of post-mining areas requires reliable information on potential deformation risk zones, which may be difficult to obtain due to a lack of necessary data. This study aimed to investigate and understand the secondary deformation processes in the underground mining area of the former "Babina" lignite mine, located in the unique glaciotectonic environment of the Muskau Arch, in western Poland. A combination of GIS-based historical mapping, geophysical 2D/3D microgravimetry, and Electrical Resistivity Tomography (ERT) measurements allowed the identification of subsidence-prone areas and the determination of potential factors of sinkhole development. The latter are associated with anthropogenic transformation of rock mass and hydrogeological conditions, by shallow underground mining. The results confirmed that multi-level mining of coal deposits in complex and complicated glaciotectonic conditions cause discontinuous deformations, and may be hazardous as long as 50 years after the end of mining operations. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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The interferometric synthetic aperture radar (InSAR) technique is used to detect surface deformations in the French Nord-Pas-de-Calais coal mining basin. Several subsiding areas had already been observed at the sites of Lens, Billy-Montigny, Courrieres and Ostricourt during the 1992-2000 period. InSAR deformation measurements are compared with ground-based levelling measurements and an analysis of the results shows a good agreement for the relative deformations. However, the InSAR study reveals a systematic bias of the absolute levelling values. Our interpretation is that the stability points of the ground-based monitoring network probably moved during the study period. Such cross-checking is particularly important considering the current legal value of the levelling measurements. [ABSTRACT FROM AUTHOR]

The article discusses the history of coal mining in Germany including the establishment of RAG Aktiengesellschaft, the formation of RAG Stiftung foundation and the development of optimized mine water concepts.