Search Results (648)

To reveal the real deformation behavior and control mechanism of surrounding rock in hard rock drifts under deep high-stress conditions, a systematic study was conducted involving engineering geological investigation, in situ monitoring of surrounding rock microstrain, and numerical simulation, taking the −1465 m deep main drift of Shaling Gold Mine as the engineering background. Joint and fissure characteristics of the surrounding rock were acquired via the traverse method, and dominant joint sets were identified to evaluate rock mass integrity, providing a geological basis for deformation analysis. On this premise, vibrating wire microstrain sensors were employed to continuously monitor the time-dependent deformation of surrounding rock at different depths in the drift roof and two sidewalls. The strain evolution law of deep hard rock surrounding rock under the combined action of excavation disturbance and high ground stress was systematically analyzed. The results demonstrate that the surrounding rock is dominated by compressive strain in the early stage after excavation, which gradually transforms into tensile strain over time, exhibiting distinct time-dependent deformation characteristics. The deformation magnitude of the surrounding rock decreases significantly with increasing distance from the drift exposure surface, and the overall deformation amplitude of the roof is greater than that of the two sidewalls. Integrating the monitoring results with the surrounding rock structural characteristics, a combined support scheme of “resin rock bolt + wire mesh + shotcrete” was proposed, and its control effect was verified using RS2 numerical simulation. The simulation results indicate that this support system can effectively constrain the near-surface surrounding rock deformation, reduce the degree of stress concentration, and significantly improve drift stability. The research findings provide engineering references for understanding the surrounding rock deformation and optimizing support parameters of deep hard rock drifts in metal mines. Full article

Under deep mining conditions, coal and rock masses are subjected to high in situ stress and strong mining-induced disturbances, leading to intensified stress unloading, concentration, and redistribution processes. The stability of surrounding rock is therefore closely related to mine safety. Direct, real-time, and continuous monitoring of in situ stress magnitude, orientation, and evolution is a critical requirement for deep underground engineering. To overcome the limitations of conventional stress monitoring methods under high-stress and strong-disturbance conditions, a novel in situ stress monitoring device was developed, and its performance was systematically verified through laboratory experiments. Typical unloading–reloading and biaxial unequal stress paths of deep surrounding rock were adopted. Tests were conducted on intact specimens and specimens with initial damage levels of 30%, 50%, and 70% to evaluate monitoring performance under different degradation conditions. The results show that the device can stably acquire strain signals throughout the entire loading–unloading process. The inverted monitoring stress exhibits high consistency with the loading system in terms of evolution trends and peak stress positions, with peak stress errors below 5% and correlation coefficients (R²) exceeding 0.95. Although more serious initial damage increases high-frequency fluctuations in the monitoring curves, the overall evolution pattern and unloading response remain stable. Combined acoustic emission results further confirm the reliability of the monitoring outcomes. These findings demonstrate that the proposed device enables accurate and dynamic in situ stress monitoring under deep mining conditions, providing a practical technical approach for surrounding rock stability analysis and disaster prevention. Full article

Accurate detection of pressure-relief boreholes is crucial for evaluating drilling quality and monitoring safety in coal mine roadways. Nevertheless, the highly challenging underground environment—characterized by insufficient lighting, severe dust and water mist disturbances, and frequent occlusions—poses substantial difficulties for current object detection approaches, particularly in identifying small-scale and low-visibility targets. To effectively tackle these issues, a lightweight and robust detection framework, referred to as YOLO-DFBL, is developed using the YOLOv11n architecture. The proposed approach incorporates a DualConv-based lightweight convolution module to optimize the efficiency of feature extraction, a Frequency Spectrum Dynamic Aggregation (FSDA) module for noise-robust enhancement, and a Biformer (Bi-level Routing Transformer)-based routing attention mechanism for improved long-range dependency modeling. In addition, a Lightweight Shared Convolution Head (LSCH) is incorporated to effectively decrease the overall model complexity. Experimental results on a real coal mine roadway dataset demonstrate that YOLO-DFBL achieves an mAP@50:95 of 78.9%, with a compact model size of 1.94 M parameters, a computational complexity of 4.7 GFLOPs, and an inference speed of 157.3 FPS, demonstrating superior accuracy–efficiency trade-offs compared with representative lightweight YOLO variants and classical detectors. Field experiments under challenging low-illumination and occlusion environments confirm the robustness of the proposed approach in real mining scenarios. The developed method enables reliable visual perception for underground drilling equipment and facilitates safer and more intelligent operations in coal mine engineering. Full article

Underground coal mining-induced subsidence threatens farmland resources and ecological sustainability in coal–grain overlapping regions with high groundwater tables, making concurrent mining and reclamation a critical management need. Previous studies have not systematically compared the integrated effects of mining sequence, extraction method, and panel optimization on subsidence control and reclamation efficiency in such regions. This study designed six mining schemes, integrating these three technical factors to investigate spatiotemporal subsidence evolution and the performance of deep digging–shallow filling reclamation. Findings reveal that mining design synergistically regulates short-to-mid-term subsidence: deep–thin seam-first skip mining eliminates initial severe subsidence damage, while shallow-thick seam-first sequential mining induces the most severe early-stage ecological disturbance. After a full extraction of both coal seams, long-term surface damage converges to 2374 ha (1509 ha severe damage), dictated by total extracted coal volume and inherent geological conditions. Reclamation efficiency depended on earthwork availability and terrain adaptability, with the optimal scheme achieving a reclamation rate of 65.00%. The findings identify mining strategies that balance subsidence mitigation and farmland restoration, providing actionable insights for sustainable mining in high-groundwater coal–grain overlapping regions. Full article

To investigate the mechanical properties, energy evolution, and failure behavior of coal–rock composite structures under mining disturbances, a mining-induced stress path was designed based on the actual stress evolution ahead of a mining face. Triaxial tests were carried out under these stress conditions on coal–rock composite samples at various confining pressures, supplemented by conventional triaxial compression tests for comparison. The results show that the coal–rock composite samples exhibited marked brittle failure under mining-induced stress, with no sign of the brittle–ductile transition observed in conventional triaxial tests as the confining pressure increased. Using dual circumferential extensometers, it was found that the circumferential deformation of the coal and rock was initially governed by their intrinsic mechanical properties and later controlled by crack propagation. At higher confining pressures, the growth rate of circumferential strain at failure increased significantly, indicating that deeper excavations result in more severe unloading-induced failure. Comparative analysis revealed that the coal component had a higher elastic energy density and faster energy accumulation and release rates than the rock, identifying coal as the dominant medium for elastic energy storage and release within the composite samples. Furthermore, at peak stress in mining-induced stress tests, the coal showed less circumferential deformation than in conventional tests, while the rock exhibited the opposite trend, confirming the presence of a bonding constraint effect at the coal–rock interface. These findings enhance our understanding of the mechanical behaviors and failure mechanisms of coal–rock composites under mining disturbances, thus providing practical guidance for ensuring safety and efficiency in deep coal mining. Full article

The sustainability of resources and ecological integrity are significantly influenced by land use and land cover change (LULCC) dynamics, particularly in ecotonal semi-arid regions where biome transitions are highly sensitive to anthropogenic disturbance and climatic variability. This study aims to assess historical LULCC dynamics and spatial reconfiguration across nine classes (grassland, shrubland, wetlands, forestland, waterbodies, farmed land, built-up land, bare land, and mines/quarries) in the C5 Secondary Drainage Region of South Africa over the three periods 1990–2014, 2014–2022, and 1990–2022. Using the South African National Land Cover datasets and the TerrSet liberaGIS v20.03 Land Change Modeller, this research applied post-classification comparison, transition matrices, asymmetric gain–loss metrics, and patch-based landscape analysis to quantify the magnitude, direction, source–sink dynamics, and spatial reconfiguration of LULCC. Results showed that between 1990 and 2014, Shrubland expanded markedly (+49.1%), primarily at the expense of Grassland, Wetlands, and Bare land, indicating bush encroachment and hydrological stress. From 2014 to 2022, the trend reversed as Grassland increased substantially (+261.2%) while Shrubland declined sharply (−99.3%). Forestland also regenerated extensively (+186%) along riparian corridors, and Waterbodies expanded more than fivefold (+384.6 km²). Over the long period between 1990 and 2022, Built-up land (+30.6%), Cultivated land (+16%), Forestland (+140%), Grassland (+94.4%), and Waterbodies (+25.6%) increased, while Bare land (−58.1%), Mines and Quarries (−56.1%), Shrubland (−98.9%), and Wetlands (−82.5%) decreased. Asymmetric analysis revealed strongly directional transitions, with early Grassland-to-Shrubland conversion likely driven by grazing pressure, fire suppression, and climate variability, followed by a later Shrubland-to-Grassland reversal consistent with fire, herbivory, and ecotonal climate sensitivity. LULC dynamics in the C5 catchment show class-specific spatial reconfiguration, declining landscape diversity (SHDI 1.3 → 0.9; SIDI 0.7 → 0.43), and patch metrics indicating urban and cultivated fragmentation, shrubland loss, and grassland consolidation. Based on these quantified trajectories, we recommend targeted catchment-scale land management, shrubland restoration, and monitoring of anthropogenic hotspots to support ecosystem services, hydrological stability, and sustainable land use in ecotonal regions. Full article

This study aims to address the pronounced stress concentration in roadway-surrounding rock under conditions of multiple thick and hard roof strata at Xiao jihan coal mine, China. The work was carried out on the 13216 working mining face as the engineering background. A systematic investigation was conducted using a combination of theoretical analysis, numerical simulation, and field experiments. Under double mining disturbance, the lower thick hard roof behaves as a cantilever beam and the upper hard roof strata form a masonry beam structure, producing strong stress transfer to the roadway. The mechanical model indicates a peak stress of 28.90 MPa, 18.34 MPa higher than the in situ stress. Hydraulic roof cutting was designed at the upper thick hard roof horizon. UDEC simulations show that the vertical stress decreases from 26.10 MPa to 13.20 MPa. Field monitoring confirms pressure relief: the non-cutting zone shows a peak of 30.75 MPa, while the roof-cutting zone drops to 22.51 MPa, a 24.62% reduction. The findings of this study provide practical guidance for lateral structure regulation under similar geological and mining conditions. Full article

During layered mining of extra-thick coal seams in deep rock-burst-prone mines, a thick bottom coal layer facilitates the accumulation of elastic strain energy in the floor strata. This stored energy may be released under mining-induced disturbances during retreat, thereby triggering rock-burst events. To mitigate floor energy accumulation at the lower-slice working face of extra-thick coal seams, previous studies have primarily adopted floor blasting for pressure relief. However, conventional blasting is often associated with poor energy utilization and limited controllability of the pressure-relief range, which hampers achieving the intended relief performance. Accordingly, this study proposes a shaped charge blasting scheme to reduce floor energy accumulation. ANSYS/LS-DYNA simulations and UDEC-based energy analyses, together with theoretical analysis and field validation, were conducted to clarify the mechanism of directional fracture propagation and the evolution of floor elastic energy before and after blasting. The results showed that the synergistic effects of the high-velocity jet and quasi-static pressure in shaped charge blasting generated a through-going fracture aligned with the maximum horizontal principal stress. This fracture effectively segmented the high-stress region in the floor and increased the maximum fracture length along the shaped charge direction to 10–13 times that achieved by conventional blasting. UDEC simulations and theoretical analysis indicated that the peak elastic energy in the floor was reduced by up to 54.08% after shaped charge blasting. Field measurements further showed that shaped charge blasting limited the maximum roadway floor heave to 300 mm and reduced floor deformation by 35–42% compared with the case without pressure relief. Overall, shaped charge blasting effectively blocks stress-transfer pathways and improves energy dissipation efficiency, providing theoretical support and a practical technical paradigm for safe and efficient mining of deep extra-thick coal seams. Full article

The Campos Rupestres, ancient and nutrient-poor mountaintop ecosystems in Brazil, harbor exceptional biodiversity and endemism but face severe threats from mining and urban expansion. Native grasses (Poaceae), represented by nearly 300 documented species—many of them poorly studied—are fundamental elements of these ecosystems. They provide critical ecological services, including soil stabilization, enhancing carbon storage and nutrient cycling, regulating water availability, and resilience to disturbances. This review synthesizes current knowledge on the diversity, functions, and propagation of Campos Rupestres grasses, with emphasis on their potential in ecological restoration. Despite their ecological importance, large-scale use of native grasses remains incipient, constrained by limited knowledge of reproductive biology, low seed viability, and scarce commercial seed availability. Advances in propagation include seedling and plug production, vegetative propagation, and rescue/reintroduction strategies, which have shown promising results in post-mining restoration. However, reliance on seed collection from natural populations risks depleting already limited genetic resources, highlighting the need for ex situ production systems. Expanding research on taxonomy, ecology, and cost-effective propagation methods, alongside supportive policy and market development, is crucial for integrating native grasses as cornerstone species in restoration programs. Bridging these gaps will enhance biodiversity conservation and restoration in one of the world’s most threatened megadiverse systems. Full article

Surface deformation induced by the extraction of natural resources constitutes a non-stationary spatiotemporal process. Modeling surface deformation time series obtained through Interferometric Synthetic Aperture Radar (InSAR) technology using deep learning methods is crucial for disaster prevention and mitigation. However, the complexity of model hyperparameter configuration and the lack of interpretability in the resulting predictions constrain its engineering applications. To enhance the reliability of model outputs and their decision-making value for engineering applications, this study presents a workflow that combines a Tree-structured Parzen Estimator (TPE)-based Bayesian optimization approach with ensemble inference. Using the Rhineland coalfield in Germany as a case study, we systematically evaluated six deep learning architectures in conjunction with various spatiotemporal coding strategies. Pairwise comparisons were conducted using a Welch t-test to evaluate the performance differences across each architecture under two parameter-tuning approaches. The Benjamini–Hochberg method was applied to control the false discovery rate (FDR) at 0.05 for multiple comparisons. The results indicate that TPE-optimized models demonstrate significantly improved performance compared to their manually tuned counterparts, with the ResNet+Transformer architecture yielding the most favorable outcomes. A comprehensive analysis of the spatial residuals further revealed that TPE optimization not only enhances average accuracy, but also mitigates the model’s prediction bias in fault zones and mineralize areas by improving the spatial distribution structure of errors. Based on this optimal architecture, we combined the ten highest-performing models from the optimization stage to generate a quantile-based susceptibility map, using the ensemble median as the central predictor. Uncertainty was quantified from three complementary perspectives: ensemble spread, class ambiguity, and classification confidence. Our analysis revealed spatial collinearity between physical uncertainty and absolute residuals. This suggests that uncertainty is more closely related to the physical complexity of geological discontinuities and human-disturbed zones, rather than statistical noise. In the analysis of super-threshold probability, the threshold sensitivity exhibited by the mining area reflects the widespread yet moderate impact of mining activities. By contrast, the fault zone continues to exhibit distinct high-probability zones, even under extreme thresholds. It suggests that fault-controlled deformation is more physically intense and poses a greater risk of disaster than mining activities. Finally, we propose an engineering decision strategy that combines uncertainty and residual spatial patterns. This approach transforms statistical diagnostics into actionable, tiered control measures, thereby increasing the practical value of susceptibility mapping in the planning of natural resource extraction. Full article

The repeated extraction of coal seams in the Loess Plateau mining region has greatly increased the severity of surface deformation and associated damage. Accurately characterizing the spatio-temporal evolution of subsidence and the underlying mechanisms is a critical engineering challenge for mining safety. Taking the Dafosi Coal Mine located in the loess gully region as a case study, this paper thoroughly examines the variations in surface deformation and damage characteristics caused by single and repeated seam mining. The analysis integrates surface movement monitoring data, global navigation satellite system (GNSS) dynamic observations, field surveys, unmanned aerial vehicle (UAV) photogrammetry, and numerical simulation methods. Notably, to ensure the accuracy of prediction parameters, a refined Particle Swarm Optimization (PSO) algorithm incorporating a neighborhood-based mechanism was employed specifically for the inversion of probability integral parameters. The results indicate that the subsidence factor and horizontal movement factor increase markedly following repeated mining. The maximum surface subsidence velocity also increases substantially, and this acceleration remains evident after normalizing by mining thickness and face-advance rate. The fore effective angle is smaller in repeated mining than in single-seam mining, and the duration of surface movement is substantially extended. Repeated mining fractured key strata and caused a functional transition from the classic three-zone response to a two-zone connectivity pattern, while the thick loess cover responds as a disturbed discontinuous-deformation layer, which together aggravates step-like and slope-related damage. The severity of surface damage is strongly influenced by topographic features and geotechnical properties. These findings demonstrate that the proposed integrated approach is highly effective for geological hazard assessment and provides a practical reference for engineering applications in similar complex terrains. Full article

This study presents the application of ground-penetrating radar (GPR) in the investigation of historical metal ore mining sites in the Lower Silesia region of Poland. The paper outlines the principles of the GPR method and details the measurement procedures used during fieldwork. GPR has proven to be an effective, non-invasive tool for identifying inaccessible or previously unknown underground mining structures, such as shafts, tunnels, and remnants of mining infrastructure. This capability is particularly valuable in the context of extensive and complex post-mining landscapes characteristic of Lower Silesia. The research presents findings from selected sites, demonstrating how GPR surveys facilitated the detection and subsequent archaeological exploration of historical workings. In several cases, the method enabled the recovery of access to underground features, which were then subjected to detailed documentation and preservation efforts. Following necessary safety and adaptation measures, some of these sites have been successfully opened to the public as part of regional tourism initiatives. The study confirms the utility of GPR as a key instrument in post-mining archaeology and mining heritage conservation, offering a rapid and reliable means of mapping subsurface structures without disturbing the terrain. Full article

To address the issue of insufficient trajectory tracking accuracy and the stability of distributed drive mining dump trucks under complex working conditions, this paper proposes a model predictive control (MPC) strategy based on genetic-particle swarm optimization (GAPSO). This strategy overcomes the limitations of traditional MPC controllers—where the weight matrix is fixed—by constructing a hierarchical optimization architecture that enables adaptive weight adjustment. An MPC-based trajectory tracking controller is developed using a three-degree-of-freedom vehicle dynamics model. Furthermore, to address the challenge of tuning MPC weight parameters, a GAPSO-based fusion optimization algorithm is introduced. This algorithm integrates the global search capability of genetic algorithms with the local convergence advantages of particle swarm optimization, enabling joint optimization of the state and control weight matrices. Simulation results demonstrate that under complex scenarios such as double lane change maneuvers, varying vehicle speeds, and different road adhesion coefficients, the proposed GAPSO-MPC controller significantly outperforms conventional MPC and PSO-MPC approaches in terms of lateral position tracking root mean square error. The method effectively enhances the robustness of trajectory tracking for distributed drive mining vehicles under disturbance conditions, offering a viable technical solution for high-precision control in autonomous mining systems. Full article

This study focuses on the Lujiang Alum Mine, analyzing sources of acid mine drainage (AMD) generated during remediation activities. A numerical model of groundwater flow was constructed to simulate and predict the causes of AMD under the influence of remediation measures. Concurrently, hydrogen and oxygen stable-isotope-tracing techniques were employed to elucidate the pathways through which AMD occurred and the mechanisms underlying water acidification. A fully mixed model was established to quantify the rates of contribution from different water sources. The results indicate that the annual amount of acidic wastewater produced under the influence of disturbance via remediation is approximately 3.29 × 10⁵ m³. The fully mixed model based on environmental isotopes further revealed that the discharge of water from the first branch of the +85 m adit serves as the primary cause of AMD during the wet, normal, and dry seasons, with a contribution exceeding 50%. This is followed by recharge from Tianchi Lake, accounting for approximately 20–30%. In contrast, the contributions from seepage water from the roof of the +85 m adit and water from the Xiaofanshan Inclined Shaft are relatively minor. Based on these findings, we propose targeted strategies for source prevention and end-of-pipe treatment of AMD in the mining area. This work provides scientific support for the ongoing ecological restoration project at the Lujiang Alum Mine and offers valuable insights for AMD management in similar mines. Full article

Against the background of global energy transformation and low-carbon development, numerous difficult-to-mine coal resources (e.g., deep, thin coal seams and low-quality coal) remain underdeveloped, leading to potential resource waste. This study systematically summarizes the feasibility of developing these resources via underground coal gasification (UCG) technology, clarifies its basic chemical/physical processes and typical gas supply/gas withdrawal arrangements, and establishes an analytical framework covering resource utilization, gas production quality control, environmental impact, and cost efficiency. Comparative evaluations are conducted among UCG, surface coal gasification (SCG), natural gas conversion, and electrolysis-based hydrogen production. Results show that UCG exhibits significant advantages: wide resource adaptability (recovering over 60% of difficult-to-mine coal resources), better environmental performance than traditional coal mining and SCG (e.g., less surface disturbance, 50% solid waste reduction), and obvious economic benefits (total capital investment without CCS is 65–82% of SCG, and hydrogen production cost ranges from 0.1 to 0.14 USD/m³, significantly lower than SCG’s 0.23–0.27 USD/m³). However, UCG faces challenges, including environmental risks (groundwater pollution by heavy metals, syngas leakage), geological risks (ground subsidence, rock mass strength reduction), and technical bottlenecks (difficult ignition control, unstable large-scale production). Combined with carbon capture and storage (CCS) technology, UCG can reduce carbon emissions, but CCS only mitigates carbon impact rather than reversing it. UCG provides a large-scale, stable, and economical path for the efficient clean development of difficult-to-mine coal resources, contributing to global energy structure transformation and low-carbon development. Full article