Legnica-Glogow Copper District Research Articles

Geomechanical Analysis of the Main Roof Deformation in Room-and-Pillar Ore Mining Systems in Relation to Real Induced Seismicity

Rockbursts represent one of the most serious and severe natural hazards emerging in underground copper mines within the Legnica–Glogow Copper District (LGCD) in Poland. The contributing factor determining the scale of this event is mining-induced seismicity of the rock strata. Extensive expertise of the copper mining practitioners clearly indicates that high-energy tremors are the consequence of tectonic disturbances or can be attributed to stress/strain behaviour within the burst-prone roof strata. Apparently, seismic activity is a triggering factor; hence, attempts are made by mine operators to mitigate and control that risk. Underlying the effective rockburst control strategy is a reliable seismicity forecast, taking into account the causes of the registered phenomena. The paper summarises the geomechanics analyses aimed to verify the actual seismic and rockburst hazard levels in one of the panels within the copper mine Rudna (LGCD). Two traverses were designated at the face range and comparative analyses were conducted to establish correlations between the locations of epicentres of registered tremors and anomaly zones obtained via analytical modelling of changes in stress/strain behaviours within the rock strata. The main objective of this study was to evaluate the likelihood of activating carbonate/anhydrite layers within the main roof over the excavation being mined, with an aim to verify the potential causes and conditions which might have triggered the registered high-energy events. Special attention is given to two seismic events giving rise to rockbursts in mine workings. Results seem to confirm the adequacy and effectiveness of solutions provided by mechanics of deformable bodies in the context of forecasting the scale and risk of dynamic phenomena and selecting the appropriate mitigation and control measures in copper mines employing the room-and-pillar mining system.

Geomechanical and Technical Aspects of Torpedo Blasting under Seismic and Rockburst Hazard Conditions in Legnica–Glogow Copper District Mines

Geomechanical and Technical Aspects of Torpedo Blasting under Seismic and Rockburst Hazard Conditions in Legnica–Glogow Copper District Mines

Impact of mining-induced seismicity on land subsidence occurrence

Mining-induced seismicity can damage buildings and surface infrastructure and cause fatalities. It is a growing concern, owing to the sudden occurrence of seismic events, lack of effective prediction capabilities, and associated consequences. In this study, we analyzed 13 high-energy mining-induced earthquakes from 2016 to 2020 in Poland's Legnica-Glogow Copper District (LGCD), based on data recorded by the Induced Seismicity-European Plate Observing System (IS-EPOS). We used European Space Agency (ESA) Sentinel-1 Copernicus satellite radar images, to study the co-seismic subsidence in the region. Additionally, we employed volumetric point source approximation and a Bayesian inverse modeling scheme to estimate the location and strength of subsurface collapses from the land subsidence data. Finally, we correlated the geological constraints with the land subsidence and earthquake source parameters. The interferometric synthetic aperture radar (InSAR) displacement maps portrayed maximum line-of-sight (LOS) displacements of −144 mm and − 124 mm in ascending and descending images, respectively, with maximum land subsidence reaching −142 mm. Notably, only a few earthquakes with large magnitudes caused land subsidence. There was a significant correlation between earthquake magnitude and land subsidence; the greater the thickness of the loose Quaternary strata, the smaller the land subsidence. According to the inversion results, the focal depths of the collapses associated with the earthquakes were 437–669 m. However, the estimated collapse depths were situated above the mining exploitation fields, within the rigid Triassic rock layers. The associated collapse energy was 1.62 times greater than the seismic energy, indicating aseismic deformation in the field. Additionally, we observed spatial discrepancy between the location of the earthquake epicenters and the maximum land subsidence. Thus, our study can improve the current understanding of the impact of mining-induced seismicity, the occurrence of associated land subsidence, and seismic mechanisms in mining areas.

Influence of a Type of Rock Mass on the Stability of Headings in Polish Underground Copper Mines Based on Boundary Element Method

This paper presents the results of a numerical analysis of the impact of rock mass geomechanical parameters on the stability of preparatory headings located within the Legnica-Glogow Copper District. The paper shows the results of numerical calculations prepared for headings driven in two rock mass types with different strength and deformation parameters, which allow illustrating their influence on the safety of mining performed in underground copper ore mines. Numerical modeling was performed using the Examine2D 7.0 software, in the plane strain state. Numerical simulations were performed for an isotropic and for a homogenous medium. The rock medium was described with an elastic model. The parameters of the rock mass for numerical modeling were calculated using the Hoek–Brown classification. The Coulomb–Mohr strength criterion was adopted as a measure for assessing the rock mass effort. Numerical simulations confirmed the dependance between the stability of the analyzed excavations and rock mass geomechanical parameters.

ANALYSIS OF MINING-INDUCED TERRAIN DEFORMATION USING MULTITEMPORAL DISTRIBUTED SCATTERER SAR INTERFEROMETRY

Abstract. This work addresses a methodology based on the Interferometric Synthetic Aperture Radar (InSAR) to analyse and monitor ground motion phenomena induced by underground mining activities, in the Legnica-Glogow Copper District, south-western Poland. Two stacks of ascending and descending Sentinel-1 Synthetic Aperture Radar (SAR) images are processed with a small baseline multitemporal approach. A simple method to select interferograms with high coherence and eliminated images with low redundancy is implemented to optimize the interferogram netwrork. The estimated displacement maps and time series show the effect of both linear and impulsive ground motion and are validated against Global Navigation Satellite System (GNSS) measurements.

A Multi-Temporal Small Baseline Interferometry Procedure Applied to Mining-Induced Deformation Monitoring

This work addresses a methodology based on the interferometric synthetic aperture radar (InSAR) applied to analyze and monitor ground-motion phenomena induced by underground mining activities in the Legnica-Glogow copper district, south-western Poland. The adopted technique employs an InSAR processing chain that exploits a stack of Sentinel-1 synthetic aperture radar (SAR) images using a small baseline multitemporal approach. Interferograms with small temporal baselines are first selected, then their network is optimized and reduced to eliminate noisy data, in order to mitigate the effect of decorrelation sources related to seasonal phenomena, i.e., snow and vegetation growth, and to the radar acquisition geometry. The atmospheric disturbance is mitigated using a spatio-temporal filter based on the nonequispaced fast Fourier transform. The estimated displacement maps and time series show the effect of both linear and impulsive ground motion and are validated against global navigation satellite system (GNSS) measurements. In this context, a significant threat to the built environment is represented by seismic tremors triggered by underground mining activities, which are analyzed using the proposed method to integrate the information gathered by in situ seismometer devices.

Tracking Deformation Processes at the Legnica Glogow Copper District (Poland) by Satellite InSAR—I: Room and Pillar Mine District

Mining exploitation leads to slow or rapid ground subsidence resulting from deformation until the collapse of underground post-mining voids following excavation activities. Satellite SAR interferometry capabilities for the evaluation of ground movements allows the monitoring of intensive surface mine subsidence and can provide new knowledge about the risks in the mining industry. This work integrates both conventional and advanced Differential SAR Interferometry (DInSAR) to study the ground subsidence in the Legnica Glogow Copper District (LGCD, Poland) by processing about 400 Sentinel-1 images from October 2014 to April 2019. Even without field data and information on past and ongoing excavation activities, the DInSAR approach allowed us to identify 30 troughs of subsidence, ranging from 500 m to 2.5 km in diameter, which in some cases, took place several times during the analyzed time span. The cumulative subsidence in 4 years and 7 months exceeds 70 cm in several zones of the LGCD. The sub-centimetric precision achieved by advanced analysis (A-DInSAR), allowed us to monitor the real extent of the mining influence area on the surface, with deformation velocities of up to 50 mm/year. The ground deformation detected at LGCD can be due to both mining-induced tremors and roof subsidence above the underground excavation rooms. As deformations do not occur concurrently with tremors, this can be related to excavation activities or to degradation of abandoned mines.

Tracking Deformation Processes at the Legnica Glogow Copper District (Poland) by Satellite InSAR—II: Żelazny Most Tailings Dam

The failures of tailings dams have a major negative impact on the economy, surrounding properties, and people’s lives, and therefore the monitoring of these facilities is crucial to mitigate the risk of failure, but this can be challenging due to their size and inaccessibility. In this work, the deformation processes at Żelazny Most tailings dam (Poland) were analyzed using satellite Ad-vanced Differential SAR Interferometry (A-DInSAR) from October 2014 to April 2019, showing that the dam is affected by both settlements (with a maximum rate of 30 mm/yr), and horizontal sliding in radial direction with respect to the ponds. The load of the tailings is pushing the dam forward along the glacio-tectonic shear planes located at depth, in the Pliocene clays, causing horizontal displacements at a rate up to 30 mm/yr, which could lead to a passive failure of the dam. The measured displacements have been compared with the ones observed by in situ data from the 90s to 2013, available in the literature. The outcomes indicate that intense localized deformations occur in the eastern and northern sectors of the dam, while the western sector is deforming evenly. Moreover, although the horizontal deformation had a slowdown from 2010 until 2013, it continued in 2014 to 2019 with recovered intensity. The upper and the recent embankments are affected by major settlements, possibly due to a lower consolidation degree of the most recent tailings and a larger thickness of compressible materials.

Wyodrębnianie struktury sieci Bayesowskiej z danych w prognozowaniu uszkodzeń żelbetowych budynków prefabrykowanych na terenach górniczych

This article presents the results of the research on the construction of a model for assessing the risk of damage to building structures located in mining areas. The research was based on the database on the structure, technical condition and mining impacts regarding 129 prefabricated reinforced concrete buildings erected in the industrialised large-block system, located in the mining area of the Legnica-Glogow Copper District (LGCD). The methodology of the Bayesian Belief Network (BBN) was used for the analysis. Using the score-based Bayesian structure learning approach (Hill-Climbing and Tabu-Search) as well as the selected optimisation criteria, 16 Bayesian network structures were induced. All models were subjected to quantitative and qualitative evaluation by verifying their features in the context of accuracy of prediction, generalisation of acquired knowledge and cause-effect relationships. This allowed to select the best network structure together with the corresponding optimisation criterion. The analysis of the results demonstrated that the Tabu-Search method adopting the optimisation criterion in the form of Locally Averaged Bayesian Dirichlet score (BDla) led to obtaining a model with the best features among all the selected models. The results justified the adoption of the BBN methodology as effective in the context of assessing the extent of damage to building structures in mining areas.

Dynamic response of a cable-stayed footbridge to high-energy mining tremors

In this work an analysis of the dynamic response of a cable-stayed footbridge to mining tremors typical for two main regions of mining activity in Poland, i.e. the Legnica-Glogow Copper District (LGCD) and the Upper Silesian Coal Basin (USCB) is presented. For analysis, a 3-D finite element (FE) model of the structure was created in the ABAQUS/Standard software program. As a final result, the dynamic responses of the footbridge to the typical mining tremors were delivered. For this stage, the numerical simulations were conducted with the non-uniform kinematic excitation as well as with the uniform kinematic excitation. Finally, the evaluation of two calculation approaches was also made for the studied structure.

The acceleration response spectra for legnica-glogow

Czasopismo Techniczne » 2017 » Volume 9 » The acceleration response spectra for Legnica-Glogow copper district A A A

Arsenic removal from industrial wastewater

The article presents current research on the removal of arsenic in one of copper smelter in Legnica-Glogow Copper District. Arsenic removal technology applied in the results of previous author’s researches has been described. Also, the content of arsenic in wastewater discharged into the receiver in 2012–2016 was examined. Additionally, the concentration of heavy metals in these wastewater was checked.

Applying the General Regression Neural Network to Ground Motion Prediction Equations of Induced Events in the Legnica-Głogów Copper District in Poland

This paper presents a study of the nonlinear estimation of the ground motion prediction equation (GMPE) using neural networks. The general regression neural network (GRNN) was chosen for its high learning rate. A separate GRNN was tested as well as a GRNN in cascade connection with linear regression (LR). Measurements of induced seis-micity in the Legnica-Glogow Copper District were used in this study. Various sets of input variables were tested. The basic variables used in every case were seismic energy and epicentral distance, while the additional variables were the location of the epicenter, the location of the seismic station, and the direction towards the epicenter. The GRNN improves the GMPE. The best results were obtained when the epicenter location was used as an additional input. The GRNN model was analysed for how it can improve the GMPE with respect to LR. The bootstrap resampling method was used for this purpose. It proved the statistical significance of the improvement of the GMPE. Additionally, this method allows the determination of smoothness parameters for the GRNN. Parameters derived through this method have better generalisation capabilities than the smoothness parameters estimated using the holdout method.

As, Cr, Cd, and Pb in Bee Products from a Polish Industrialized Region

AbstractBee pollen and bee bread from stationary apiaries in the southwest Polish Legnica-Glogow copper district (LGOM) were analyzed for Cr, Pb, Cd and As by ICP-AES. Their concentrations in both products were As > Cr > Pb > Cd. Concentrations in bee pollen were higher than in bee bread. Average Cr, Pb, As and Cd concentrations in bee products were 0.138, 0.093, 0.325, and 0.019 mg kg−1, respectively. Chromium was the most problematic element in bee pollen because its concentration limit was exceeded in more than 50% of the samples. Differences in Cd level between bee pollen and bread were significant (p ≤ 0.05)

Simulation of Dynamic Behaviour of RC Bridge with Steel-Laminated Elastomeric Bearings under High-Energy Mining Tremors

In the paper a detailed analysis of dynamic responses of a reinforced concrete bridge with steel-laminated elastomeric bearings to high-energy mining tremors registered in two main regions of mining activity in Poland (i.e. Upper Silesian Coal Basin and Legnica-Glogow Copper District) was presented. The representative time histories of accelerations from both regions were used as ground motion data in calculations of the dynamic response of the structure. The two-coefficient Mooney-Rivlin model was used as a constitutive model for hyperelastic non-linear elastomeric material. It was proved that the dynamic response of the bridge was strongly dependent not only on the level of vibration amplitudes but on the dominant frequency range of the mining shock typical for the mining region as well. Also the height of elastomeric bearings occurred to have considerable influence on the total dynamic response of the bridge. Two heights of bearings were analyzed: 42 mm and 85 mm. The increase of the height of bearings caused the decrease up to 25 % in the maximal principal stresses obtained in the dynamic analysis. The behaviour of elastomeric material in case of bearings 42 mm high occurred to be strongly non-linear, whereas in case of bearings 85 mm high behaviour of elastomeric material remained almost linear.

The role of static stress transfer in mining induced seismic events occurrence, a case study of the Rudna mine in the Legnica-Glogow Copper District in Poland

SUMMARY Seismicity accompanying mining exploitation results from changes in the stress field in the rock mass near the mining excavations caused by human activity. Many studies of the temporal and spatial distribution of mining induced seismicity have provided evidence for interrelations among events. Although a variety of techniques have been applied to quantify the interdependences of mining induced seismic events, the physical mechanism of interactions has not been unequivocally identified. Based on the premise that one possible cause of interactions among seismic events can be static stress transfer, we have verified statistically the role of Coulomb stress transfer in the generation process of mining induced seismicity using a series of seismic

A study of the interaction among mining-induced seismic events in the Legnica-Głogów Copper District, Poland

We applied the Coulomb stress transfer technique to investigate interactions among seismic events induced by mining works in the Rudna mine in the Legnica-Glogow Copper District in Poland. We considered events with energy greater than 105 J from the period 1993–1999.

Toxic metals in aquatic plants surviving in surface water polluted by copper mining industry

Concentrations of the metals Al, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn, as well as the macronutrients N, P, K, Ca, Mg, and S were measured in water, sediments, and the aquatic macrophytes Potamogeton pectinatus and Myriophyllum spicatum, growing in surface water receiving sewages and solid wastes from a copper smelter and a copper ore processing factory located in the Legnica-Glogow copper district in Southwest Poland. The deposition of mineral wastes in this area belong to the largest repository in Europe. The plants were able to survive at heavily contaminated sites. The concentrations of Cd (up to 0.6–1.7 μg/L in water and up to 10.1–12.9 mg/kg in sediments), Cu (up to 29–48 μg/L in water and up to 4.6–5.6 g/kg in sediments), Pb (up to 1.5–2.2 g/kg in sediments), and Zn (up to 167–200 μg/L in water and up to 1.4–1.8 g/kg in sediments) seriously exceeded background values. P. pectinatus was able to survive tissue concentrations (in mg/kg) of up to 920 Cu, 6240 Mn, 98 Co, and 59 Ni, while M. spicatum survived tissue concentrations up to 1040 Cu, 6660 Mn, and 57 Co for. Enrichment ratios of elements in plant tissue and in water were much higher than those between plant tissue and sediments.