Search Results (30)

Methane emissions from underground coal mines are a significant source of greenhouse gases (GHGs) and a major safety concern. In highly methane-prone operations, a large proportion of emissions comes from low-content abandoned mine methane (LCAMM) accumulated in post-mining goafs, where concentrations usually stay below 30% CH₄. Building on the Research Fund for Coal and Steel (RFCS) REM project, this paper presents a cost–benefit analysis of a comprehensive scheme for capturing, transporting, and utilising LCAMM from post-mining goafs for electricity generation. The concept involves long-reach directional boreholes drilled behind isolation dams, a dedicated methane-reduced drainage system connected to a surface methane drainage station, and four 2 MWe gas engines designed to run on a 20–40% CH₄ mixture. Greenhouse gas performance is evaluated by comparing a “business-as-usual” scenario in which post-mining methane is combusted in gas engines to produce electricity without further GHG cost–benefit consideration. The results indicate that the project can achieve a positive net present value, highlighting the role of LCAMM utilisation for methane-intensive coal mines. The paper also explores the monetisation of non-emitted methane using the European Union Emissions Trading System (EU ETS), as well as social cost benchmarks and penalty levels consistent with the emerging EU Methane Emissions Regulation (EU MER). Full article

Degraded post-mining landscapes require reclamation strategies that ensure soil stability, environmental safety and successful vegetation establishment. This study evaluated two soil cover systems applied between 2020 and 2025 on a mining spoil heap in Libiąż, Poland: a two-layer (TL) cover with a soil substitute layer and a multilayer (ML) cover incorporating additional insulating materials. Both covers were non-saline and mildly alkaline. The applied methods supported favorable soil conditions after five years, with stable organic matter (24.48–28.26%), nitrogen (4.5–4.9 g/kg) and phosphorus (1.5–1.6 g/kg) contents, while potassium decreased markedly (from 17.1 to 6.44–6.83 g/kg), likely due to plant uptake or leaching. Leachate analyses showed low concentrations of toxic metals and salinity-related ions, confirming the environmental safety and inert properties of the soil substitute. Vegetation assessments revealed differences between reclamation systems, with Phragmites australis exhibiting greater stalk length, plant density and biomass in the TL cover. Establishment costs were also substantially lower for TL (EUR 1.65/m²) than for ML (EUR 6.14/m²). These results indicate that soil substitute covers provide a safe, cost-effective and functionally efficient reclamation option that supports circular economy principles by reusing mining waste and coal combustion by-products, while Phragmites australis enhances vegetation development and overall reclamation success. Full article

The failure mechanism of fractured rock masses under high in situ stress is crucial to the stability of deep underground engineering. This study employs the discrete element method to investigate the evolution of the excavation damage zone (EDZ) in deep-buried tunnels. Numerical models of granite were developed to analyze how confining pressure influences single fractures with varying characteristics and to compare the behavior of filled versus unfilled fractures in double-fracture configurations. The results show the following: (1) confining pressure exerts a dual role, promoting crack initiation and EDZ expansion in intact rock and exposed fractures due to stress concentration while suppressing damage near hidden filled fractures through confinement; (2) EDZ geometry is governed by fracture orientation and filling condition, with filled fractures maintaining stress continuity and raising the crack initiation stress ratio to 0.3–0.4; (3) in multi-fracture setups, unfilled fractures facilitate stress release and crack coalescence, whereas filled fractures act as barriers, diverting cracks and promoting symmetric stress redistribution; and (4) models accurately reproduced failure patterns from real rockburst cases, validating the method for predicting fracture behavior, with filled fractures reducing EDZ area by up to 44%. These findings provide theoretical support for rockburst risk assessment and support design in complex geological conditions. Full article

The article is devoted to the issues of designing the exploitation of a seam deposit in the boundary areas of underground mines in terms of minimizing the risk of dynamic phenomena. Its main goal was to attempt to demonstrate the relationship between the method of extracting resources trapped in the boundary pillar and the magnitude of the induced seismicity of the rock mass accompanying this process. The substantive considerations concerned the single-wall model and were divided into two main parts—theoretical and verification. As part of the theoretical piece, based on model studies, a geomechanical assessment of the impact of the working face advance on changes in the stress–strain behaviour occurring in the burst-prone layer in terms of the possible loss of continuity of its original structure was carried out. The starting point for the key analyses were the results of numerical simulations based on the algorithms of S. Knothe and W. Budryk’s theories in combination with classical solutions of the mechanics of deformable bodies. Two variants of mining operations in a two-sided environment of goaf were considered, differing in the direction of progress, the degree of constraint of the start and end of the face advance, and mining circumstances in the vicinity of both sides of the advancing face. As part of the verification piece, the results of model analyses were related to an example polygon of a crossing longwall in one of the functioning, rockburst USCB hard coal mines. The scope of the research included a comparison of the experimentally indicated zones of occurrence of tremor-favourable effort processes in the roof of the seam with the actual location of the seismic phenomena foci recorded during the ongoing exploitation. The considerations included in the work formed the basis for formulating conclusions of a cognitive and applicable nature. Full article

Rockburst is a dynamic disaster that frequently occurs in hard and brittle rock tunnels under high in situ stress conditions. It is influenced by multiple factors, including lithological condition, in situ stress condition, and surrounding rock mass structural condition. Rockbursts are highly destructive and difficult to predict accurately. At present, many methods have been proposed for predicting rockburst proneness. However, the above methods suffer from a lack of diversity, limited applicability, and low predictive accuracy. Therefore, based on the Analytical Hierarchy Process (AHP) method and fuzzy mathematics theory, the eight evaluation indexes (strength brittleness index, stress coefficient, elastic energy index, surrounding grade, etc.) were selected to establish the new AHP fuzzy comprehensive evaluation model. Based on the field case studies, the feasibility and accuracy of the model were validated. The results indicate that the proposed multi-index prediction model demonstrates strong feasibility and high predictive accuracy, and the model has promising application prospects. Meanwhile, the 13 recognized evaluation indexes were summarized, and an approach for accurate rockburst prediction was proposed. The predicting model and predicting approach proposed in this paper are of great significance for improving the accuracy of rockburst prediction. Full article

In response to the imperative to mitigate methane—one of the most potent greenhouse gases—this study proposes and tests an integrated workflow for designing methane drainage boreholes targeting post-mining areas in an active underground coal mine (Pniówek, Poland). The workflow combines the following: (1) forecasting methane emissions from goafs and active longwalls for 2024–2040; (2) 3D geological characterization (structural and lithofacies models); (3) selection and sealing of goaf zones; and (4) optimization of well placement, drilling, and performance evaluation of drainage boreholes, including an assessment of energy use from the recovered gas. Applying the method delineated priority capture zones and estimated recoverable rates under multiple scenarios. Preliminary field data from a borehole near seam 362/1 indicate stable methane inflow to the drainage system and a concomitant reduction in methane load within the ventilation network. The integrated design improves targeting efficiency and provides a quantitative basis for scheduling, risk management, and sizing of surface-to-underground infrastructure. The results suggest that systematic drainage of post-mining voids can enhance safety, limit fugitive emissions, and create opportunities for on-site power generation. The approach is transferable to other active mines with legacy workings, provided site-specific calibration and monitoring are implemented. Full article

Conventional geostress methods of measurement cannot reveal an accurate geostress field distribution in an engineering area, limited by both cost and prevailing geological conditions. This study introduces an improved LSTM–Attention neural network for in situ stress field inversion. By integrating long short-term memory (LSTM) networks—which capture temporal dependencies in sequential data with attention mechanisms that emphasize critical features, the proposed method addresses inherent non-linearity and discontinuity challenges in deep subsurface stress field inversion. The integrated LSTM and multi-head attention architecture extracts temporal features and weights critical information within ground stress field data. Through iterative refinement via optimizers and loss functions, this framework successfully inverts stress boundary conditions while mitigating overfitting risks. The inversion of the stress field around a hydropower station indicates that the proposed method allows accurate inversion of distribution of the geostress field; the inversion values of the maximum principal stress, intermediate principal stress, and minimum principal stress conform to those measured. This study provides a new method for accurately and reliably inverting the stress field for deep engineering geological surveys and rock mass engineering design, which has significant scientific value and engineering application prospects. The rockburst risk of chambers is evaluated according to the stress field, which shows that locations with a burial depth of 274.3 m are at moderate to weak risk of rockburst. Full article

As an important traffic and transportation roadway, tunnel engineering is widely used in important fields such as highways, railways, water conservancy, subways and mining. It is limited by complex geological conditions, harsh construction environments and poor robustness of the monitoring system. If the construction process and monitoring method are not properly designed, it will often directly induce disasters such as tunnel deformation, collapse, leakage and rockburst. This seriously threatens the safety of tunnel construction and operation and the protection of the regional ecological environment. Therefore, based on distributed fiber optic sensing technology, the full–cycle spatiotemporally continuous sensing information of the tunnel structure is obtained in real time. Accordingly, the health status of the tunnel is dynamically grasped, which is of great significance to ensure the intrinsic safety of the whole life cycle for the tunnel project. Firstly, this manuscript systematically sorts out the development and evolution process of the theory and technology of structural health monitoring in tunnel engineering. The scope of application, advantages and disadvantages of mainstream tunnel engineering monitoring equipment and main optical fiber technology are compared and analyzed from the two dimensions of equipment and technology. This provides a new path for clarifying the key points and difficulties of tunnel engineering monitoring. Secondly, the mechanism of action of four typical optical fiber sensing technologies and their application in tunnel engineering are introduced in detail. On this basis, a spatiotemporal continuous perception method for tunnel engineering based on DFOS is proposed. It provides new ideas for safety monitoring and early warning of tunnel engineering structures throughout the life cycle. Finally, a high–speed rail tunnel in northern China is used as the research object to carry out tunnel structure health monitoring. The dynamic changes in the average strain of the tunnel section measurement points during the pouring and curing period and the backfilling period are compared. The force deformation characteristics of different positions of tunnels in different periods have been mastered. Accordingly, scientific guidance is provided for the dynamic adjustment of tunnel engineering construction plans and disaster emergency prevention and control. At the same time, in view of the development and upgrading of new sensors, large models and support processes, an innovative tunnel engineering monitoring method integrating “acoustic, optical and electromagnetic” model is proposed, combining with various machine learning algorithms to train the long–term monitoring data of tunnel engineering. Based on this, a risk assessment model for potential hazards in tunnel engineering is developed. Thus, the potential and disaster effects of future disasters in tunnel engineering are predicted, and the level of disaster prevention, mitigation and relief of tunnel engineering is continuously improved. Full article

Precise forecasting of rockburst intensity categories is vital to safeguarding operational safety and refining design protocols in deep underground engineering. This study proposes an intelligent forecasting framework through the integration of k-medoids-SMOTE and the BSLO-optimized Random Forest (BSLO-RF) algorithm. A curated dataset encompassing 351 rockburst instances, stratified into four intensity grades, was compiled via systematic literature synthesis. To mitigate data imbalance and outlier interference, z-score normalization and k-medoids-SMOTE oversampling were implemented, with t-SNE visualization confirming improved inter-class distinguishability. Notably, the BSLO algorithm was utilized for hyperparameter tuning of the Random Forest model, thereby strengthening its global search and local refinement capabilities. Comparative analyses revealed that the optimized BSLO-RF framework outperformed conventional machine learning methods (e.g., BSLO-SVM, BSLO-BP), achieving an average prediction accuracy of 89.16% on the balanced dataset—accompanied by a recall of 87.5% and F1-score of 0.88. It exhibited superior performance in predicting extreme grades: 93.3% accuracy for Level I (no rockburst) and 87.9% for Level IV (severe rockburst), exceeding BSLO-SVM (75.8% for Level IV) and BSLO-BP (72.7% for Level IV). Field validation via the Zhongnanshan Tunnel project further corroborated its reliability, yielding an 80% prediction accuracy (four out of five cases correctly classified) and verifying its adaptability to complex geological settings. This research introduces a robust intelligent classification approach for rockburst intensity, offering actionable insights for risk assessment and mitigation in deep mining and tunneling initiatives. Full article

It has been found in engineering practice that the degree of rockburst risk increases when roadway excavation occurs near the stratigraphical boundary of different lithologies. This study uses the 1276 m deep-buried roadway of a lead–zinc mine in Yunnan, China, as its engineering background. Based on a numerical analysis of this case, it investigates the mechanical behavior of surrounding rocks in different lithological formations and explores the causes of excavation-induced rockburst. Additionally, by changing the excavation strategy in a numerical simulation, the influence of the direction of roadway excavation on the degree of rockburst risk in the construction of different lithological formations is assessed. The results are summarized as follows: (1) When the tunnel passes from the C₁b stratum (limestone) to the D₃zg stratum (dolomite), an abnormal stress zone forms in the roof rock strata of the D₃zg stratum (the lower plate of the stratum boundary). The rockburst risk level was evaluated by introducing the numerical rockburst index in this abnormal stress zone, which aligns closely with on-site rockburst investigation results. The rockburst risk is the greatest in the abnormal stress zone, which provides an external energy storage environment for the development of rockburst disasters. (2) Near the stratum boundary, the rockburst risk level when excavating from the D₃zg stratum to the C₁b stratum is greater than that when excavating from the C₁b stratum to the D₃zg stratum. The direction of tunnel excavation significantly affects the rockburst risk level during construction that crosses different lithological strata. These findings can provide a theoretical basis for the construction design of similar underground projects. Full article

Treating poultry manure with calcium compounds is the primary technique for inactivating toxic pathogens such as bacteria, fungi, or viruses and decreasing the risk of biological contaminant release into the environment. On the other hand, the preferable method for reducing its volume is incineration with the aim of obtaining highly concentrated fertilizer. This paper presents the optimization of the biological deactivation of fresh poultry manure using calcium hydroxide via central composite design and response surface methodology. The results revealed that the optimum parameters required to decrease the number of E. coli bacteria to below the acceptable level (1000 CFU/g) were 5.0 wt% Ca(OH)₂ at 22 °C and an exposure time of 209 h. A regression analysis showed a good fit of the approximated parameters to the experimental data (R² = 98%, R_adj.² = 97%). Additionally, laboratory tests involving ash samples obtained from the incineration of poultry manure with the addition of 5 wt% calcium hydroxide (T = 500 °C, t = 5 h) intended as a fertilizer for degraded soils were performed. The analysis revealed that the content of pure manure ash in the sample incinerated with Ca(OH)₂ was approximately 47.5%. An X-ray diffraction analysis of the ash sample revealed that the main crystalline component was calcite (67.5 wt% CaCO₃), the phases containing phosphorus were apatite (3 wt%) and hydroxyapatite (3 wt%), whereas the source of the bioavailable form of phosphorus was the amorphous phase (15.5 wt%). An analysis of the ash extracts in a 2% citric acid solution revealed that the phosphorus concentration (287 mg/L) was two times lower than that of potassium (661 mg/L). The best results of phytotoxicity tests with Sinapis alba were obtained for soils containing no more than 1.0 wt% ash with calcium hydroxide. Full article

The rehabilitation of post-mining sites is crucial due to the severe environmental impacts of mining, including land degradation, heavy metal pollution, and loss of biodiversity. Effective reclamation strategies are essential to reverse these impacts and enable sustainable land use. This study presents the possibility of the rehabilitation of a post-mining area in Velenje, Slovenia, using artificial soils made from combustion by-products amended with lignite and organic compost, and explores the potential of lignite mine water for irrigation. This approach introduces an innovative solution that differs from the traditional methods of rehabilitating degraded areas. Physicochemical and phytotoxicity tests were conducted to determine the quality of the soil substitutes. The analysis revealed that the pH, salinity, and chemical composition of soils positively impacted Sinapis alba growth as a test plant, with the most promising compositions containing 20–30% of lignite by weight as a replacement for organic compost. Irrigation water quality parameters, such as electrical conductivity (0.87 dS/m), the sodium absorption ratio (2.09 meq/L), and boron content (0.05 mg/L), indicated a low soil dispersion risk, while the residual sodium carbonate (3.02 meq/L) suggested a medium risk. Although, the concentration of toxic elements did not exceed the threshold limits; the long-term irrigation with mine water requires the monitoring of the molybdenum levels. These results suggest the potential for using artificial soils and mine water in post-mining land reclamation but highlight the need for the monitoring of their quality. Full article

As one of the serious hazards in deep mining, rock instability will cause roof falls, rib spalling, rockburst, and other serious disasters. It will lead to significant casualties and property losses. Conducting risk assessments for rock instability is of significant importance. Firstly, an evaluation model called IAHP-SPA was proposed to address uncertainties in the weight determination process. Secondly, the Partial Connection Number (PCN) including the first-order PCN, the second-order PCN, the third-order PCN and the fourth-order PCN were introduced. Thus, a dynamic and comprehensive evaluation of rock instability in metal mines was obtained. Finally, the availability and reasonability of the proposed method were verified by comparing the results obtained with the number of microseismic events detected by the sensors in a metal mine. The proposed model provides a novel approach to dynamic risk assessment in mining, offering a reliable alternative for evaluating complex safety challenges. This method holds substantial potential for its practical application in the assessment and control of rock instability risks in deep metal mines, thereby improving safety and operational efficiency. Full article

Microseismic data are widely employed for assessing rockburst risks; however, significant disparities exist in the monitoring capabilities of seismic networks across different mines, and none can capture a complete dataset of microseismic events. Such differences introduce unfairness when applying the same methodologies to evaluate rockburst risks in various mines. This paper proposes a method for assessing the monitoring capability of seismic networks applicable to heterogeneous media in mines. It achieves this by integrating three gradient boosting algorithms: Extreme Gradient Boosting (XGBoost), Light Gradient Boosting Machine (LightGBM), and Categorical Boosting (CatBoost). Initially, the isolation forest algorithm is utilized for preliminary data cleansing, and feature engineering is constructed based on the relative locations of event occurrences to monitoring stations and the working face. Subsequently, the optimal hyperparameters for three models are searched for using 8508 microseismic events from the a Coal Mine in eastern China as samples, and 18 sub-models are trained. Model weights are then determined based on the performance metrics of different algorithms, and an ensemble model is created to predict the monitoring capability of the network. The model demonstrated excellent performance on the training and test sets, achieving log loss, accuracy, and recall scores of 7.13, 0.81, and 0.76 and 6.99, 0.80, and 0.77, respectively. Finally, the method proposed in this study was compared with traditional approaches. The results indicated that, under the same conditions, the proposed method calculated the monitoring capability of the key areas to be 11% lower than that of the traditional methods. The reasons for the differences between these methods were identified and partially explained. Full article

This paper presents a methodology to select the most exciting business models based on renewable energy and circular economy technologies within end-of-life coal mines to help develop a renewable-based energy sector, promote sustainable local economic growth, and maximise the number of green and quality jobs. To achieve this goal, first, a structural analysis was developed to select the technical variables that better identify this complex system. Second, a morphological analysis allowed the construction of the scenario space. Third, a multicriteria assessment was developed to achieve this goal, based on the previously assessed relevant scenarios, considering the European Green Deal policies, technical variables that characterise end-of-life coal mine environments, technology readiness level, the European taxonomy, synergistic potentials, contributions to the circular economy, and sector coupling. Finally, result indicators were selected to analyse the alternative options derived from the justification approach, considering the targets set by the European Green Deal and related taxonomy and the regional policy indicators for the Just Transition Fund. The results show that eco-industrial parks with virtual power plants represent the most appropriate business model choice, according to the scoring given to the different aspects. They may be complemented by a hydrogen production plant, provided that specific economic subventions are obtained to achieve balanced financial results. Full article