Search Results (352)

Because of its specific nature, mining activity causes numerous negative impacts on the environment, both during the exploitation phase and after it has ended. An important source of income in the Jiu Valley is represented by the Lupeni Mining Exploitation. Like any mining activity, coal exploitation causes various negative effects on the environment. The subsidence phenomenon represents a significant issue associated with coal mining in the Jiu Valley. Underground extraction of mineral deposits induces displacement of the overburden strata. Such displacements result in ground subsidence and modifications of the surface topography. The larger the voids created following the exploitation of useful mineral deposits, the more they affect the surface of the land above the exploitation through sinking, displacement, deformation, and even cracks. Secondary deformations refer to post-mining surface movements induced by delayed rock mass adjustment, manifesting as ground collapse, localized subsoil failure, or uplift driven by groundwater rebound after drainage cessation. In this paper, we aim to study the subsidence phenomenon produced by coal mining at the Lupeni Mining Exploitation using the COMSOL simulation software and applying the Barcelona Basic Model (BBM) and Modified Cam-Clay (MCC) models. Following the simulation, the behavior of the rocks could be observed in order to improve prediction accuracy to support sustainable land management in post-mining areas. Full article

Globally, the open-stope method is used in over 60% of small- and medium-sized mines because of its low cost and high initial efficiency, but it has issues like high ore loss and a great goaf-collapse risk, becoming a core bottleneck for mines’ green and sustainable development. Thus, accelerating its transition to the green backfilling method is an urgent industry need. This study focuses on Shishudi Gold Mine, Xingan Fluorite Mine, and Suichang Gold Mine, adopting a “problem diagnosis–scheme design–case verification–experience extraction” framework to analyze their economic and ecological indicators pre- and post-transition. Our results show remarkable effects: Shishudi’s ore recovery rose from 75% to 88.5%, with 300,000 tons of residual ore recovered and 100% tailing utilization; Xingan’s ore loss dropped by 12%, annual output increased by 60,000 tons, and 200,000 tons of tailings was consumed to achieve a “tailless mine”; and Suichang’s mining capacity rose from 30 tons per day (t/d) to 120 t/d, using 150,000 tons of cyanide-free tailings yearly. In this paper, the key problems of open-stope mining are identified and a transition path of “process innovation–system construction–tailing utilization–mechanization support” is summarized. Our results provide promotable technical solutions and practical references for global small- and medium-sized mines that are of great significance for driving their green and sustainable development. Full article

This study investigates slope stability in an open-pit mining area by integrating engineering geological surveys, field investigations, and laboratory rock mechanics tests. A coordinated multimethod analysis was carried out using finite element-based numerical simulations from both two-dimensional and three-dimensional perspectives. The integrated approach revealed deformation patterns across the slopes and established a multiscale analytical framework. The results indicate that the slope failure modes primarily include circular and compound types, with existing step slopes showing a potential risk of wedge failure. While the designed slope meets safety requirements under three working conditions overall, the strongly weathered layer in profile XL3 requires a slope angle reduction from 38° to 37° to comply with standards. Three-dimensional simulations identify the main deformations in the middle-lower sections of the western area and zones B and C, with faults located at the core of the deformation zone. Rainfall and blasting vibrations significantly increase surface tensile stress, accelerating deformation. Although wedges in profiles XL1 and XL4 remain generally stable, coupled blasting–rainfall effects may still induce potential collapse in fractured areas, necessitating preventive measures such as concrete support and bolt support, along with real-time monitoring to dynamically optimize reinforcement strategies for precise risk control. Full article

The overlying rock layers in a mining area may collapse or settle, subjecting pipelines to uneven forces that can lead to deformation or even fracture. This paper proposes a pipeline safety monitoring method that combines fiberoptic vibration and strain sensing to detect vibrations and deformations caused by rock layer collapse in mining zones. First, pipeline deformation monitoring under unknown force directions was investigated using fiber Bragg grating (FBG) sensing technology. Second, we constructed a mining area pipeline model and conducted vibration/deformation monitoring tests employing FBG sensors, distributed Brillouin strain sensing, and distributed fiberoptic vibration sensing technologies. The experimental results demonstrate that FBG sensor arrays deployed at 90-degree intervals can effectively identify the pipeline’s primary force direction and maximum strain, with direction angle errors of less than 5.2%. The integrated analysis of vibration and strain data enables accurate identification and measurement of extended vibration responses and pipeline deformations in open-air zones. This study establishes a comprehensive monitoring framework for ensuring pipeline safety in mining areas. Full article

This paper focuses on the issues of roof movement and ground pressure behavior in large-height mining extraction of shallow coal seams. By adopting a combined method of theoretical analysis and physical simulation experiments, it establishes a mechanical model for the rotational subsidence of key blocks and a physical simulation test model to conduct stability analysis on the rotational subsidence of key blocks, thereby revealing the characteristics and laws of roof movement. The findings indicate that the horizontal thrust during the rotational subsidence of key blocks increases non-linearly with the rotation angle, exhibiting a higher growth rate when the block size coefficient is less than 0.5. Two modes of instability—sliding and deformation—are observed for key blocks. To prevent sliding instability, the block size coefficient should be maintained below 0.75; however, sliding instability is likely to occur when the rotation angle exceeds 10°. Conversely, smaller rotation angles and larger block size coefficients reduce the likelihood of deformation instability. The reasonable working resistance of the support decreases with the increase in the rotation angle (it decreases sharply when the rotation angle exceeds 10°) and increases with the increase in the block size coefficient. Physical simulation indicates that roof movement is divided into three stages: immediate roof collapse, stratified fracturing and instability of the basic roof, and periodic fracturing of the basic roof. An increase in mining height accelerates the instability of the immediate roof, enlarges the opening of through-layer fissures, shortens the step distance of mining pressure, and heightens the risk of sudden pressure. The research results provide theoretical guidance for the safe and efficient mining with large mining height in shallow coal seams. Full article

Pre-extraction gas technology is commonly used in coal mines to extract gas from single coal seams, initial protective layers, and both unprotected and protected coal seams. With the development of drilling equipment, directional long drilling, pre-extraction, coal seam gas technology has been widely applied, and negative pressure extraction is one of the key factors affecting the effectiveness of directional long drilling gas extraction. In order to determine the reasonable length of directional long boreholes, studying the negative pressure distribution and time-varying rules within such boreholes is of great significance for guiding later borehole layout and gas extraction. The COMSOL Multiphysics software v.5.3. was used to couple and solve the dynamic model of temperature, stress, and seepage in coal-containing gas, as well as the mathematical model of negative pressure attenuation in directional long boreholes. The gas pressure distribution in the coal surrounding the directional long borehole and the distribution and time-varying law of negative pressure in the borehole were studied. Then, the distribution and time-varying law of negative pressure in directional long borehole extraction were tested on site. Research has shown that the negative pressure attenuation during directional long drilling has a relatively small impact on the effectiveness of coal gas extraction, while the negative pressure at the hole opening is the key factor affecting the effectiveness of gas extraction. In the early stage of extraction, as the drilling depth increases, the pressure loss inside the hole increases and the negative pressure inside the hole decreases. As the extraction time becomes longer, the pressure loss inside the borehole decreases and the negative pressure inside the borehole gradually returns to the negative pressure value at the orifice. The gas flow velocity inside the extraction borehole gradually increases from the bottom of the hole to the hole opening, and the flow velocity at the bottom of the hole remains basically constant. The gas flow velocity inside the hole gradually decreases with the extension of extraction time, and the smaller the distance from the extraction hole opening, the greater the flow attenuation. The collapse of drilling holes during extraction affects the attenuation of negative pressure inside the hole in the short term. As the extraction time increases, the impact of the collapse on the negative pressure inside the hole is limited. The temperature of coal can significantly affect the negative pressure and gas flow distribution inside the pores. Considering the temperature effect, the gas flow velocity inside the pores is higher and the pressure loss is lower in the short term. On-site tests have determined that the depth of ultra-long directional drilling holes is shallower than 327 m, and the negative pressure changes inside the borehole are not significantly different from the negative pressure at the hole opening. The negative pressure stabilization speed near the hole opening and bottom is fast, usually reaching its peak within 3–10 min. The negative pressure stabilization process from the borehole opening to the hole bottom shows a “fast slow fast” trend. When using double-sided extraction, the time for negative pressure to reach stability is significantly shortened compared to single-sided extraction, and double-sided extraction is beneficial for improving the effectiveness of coalbed methane extraction. Full article

To investigate the failure mechanisms of surrounding rock in deep mine tunnels and its spatio-temporal evolution patterns, a true triaxial disturbance unloading rock testing system, the acoustic emission (AE) system, and the miniature camera monitoring system were employed to conduct true triaxial graded loading tests on sandstone containing circular holes at burial depths of 800 m, 1000 m, 1200 m, 1400 m, and 1600 m. The study investigated the patterns of mechanical properties and failure characteristics of porous sandstone at different burial depths. The results showed that the peak strength of the specimens increased quadratically with increasing burial depth; the failure process of porous sandstone could be divided into four stages: the calm period, the particle ejection period, the stable failure period, and the complete collapse period; as burial depth increases, the failure mode transitions from a composite tensile–shear crack type to a shear crack-dominated type, with the ratio of shear cracks to tensile cracks exhibiting quadratic growth and reduction, respectively; the particle ejection stage is characterised by low-frequency, low-amplitude signals, corresponding to the microcrack initiation stage, while the stable failure stage exhibits a sharp increase in low-frequency, high-amplitude signals, reflecting macrocrack propagation characteristics, with the spatial evolution of their locations ultimately forming a penetrating oblique shear failure zone; and peak stress analysis indicates that as burial depth increases, peak stress during the particle ejection phase first increases and then decreases, while peak stress during the stable failure phase first decreases and then stabilises. The duration of the pre-instability calm phase shows a significant negative correlation with burial depth. The research findings provide a theoretical basis for controlling tunnel rock mass stability and disaster warning. Full article

Focusing on the issues of severe mining pressure and discontinuous surface deformation caused by the large-scale mining of multiple coal seams, and taking into account the research background of Shigetai Coal Mine in Shendong Mining Area, this study adopts physical similarity simulation, theoretical analysis, and on-site verification methods to carry out research on rock migration, stress evolution, and overlying rock fracture mechanism at shallow burial depths and in multiple-coal-seam mining. The research results indicate that as the working face advances, the overlying rock layers break layer by layer, and the intact rock mass on the outer side of the main fracture forms an arched structure and expands outward, showing a pattern of layer-by-layer breaking of the overlying rock and slow settlement of the loose layer. The stress of the coal pillars on both sides in front of and behind the workplace shows an increasing trend followed by a decreasing trend before and after direct top fracture. The stress on the bottom plate of the goaf increases step by step with the collapse of the overlying rock layer, and its increment is similar to the gravity of the collapsed rock layer. When mining multiple coal seams, when the fissures in the overlying strata of the current coal seam penetrate to the upper coal seam, the stress in this coal seam suddenly increases, and the pressure relief effect of the upper coal seam is significant. Based on the above laws, three equilibrium structural models of overlying strata were established, and the maximum tensile stress and maximum shear stress yield strength criteria were used as stability criteria for overlying strata structures. The evolution mechanism of mining damage caused by layer-by-layer fracturing and the upward propagation of overlying strata was revealed. Finally, the analysis of the hydraulic support working resistance during the backfilling of the 31,305 working face in Shigetai Coal Mine confirmed the accuracy of the similarity simulation and theoretical model. The above research can provide support for key theoretical and technological research on underground mine safety production, aquifer protection, surface ecological restoration, and source loss reduction and control. Full article

The frequent blasting in underground mines results in stress waves of different intensities, which is one of the main factors leading to backfill collapse. Improving the strength of backfill is an effective way to reduce the backfill damage. In this study, rice straw fiber and graded tailings were used as raw materials to prepare rice straw fiber-reinforced cemented tailings backfill (RSCTB). An orthogonal experimental design was employed to perform unconfined compressive strength (UCS) tests, diffusivity measurements, and Split Hopkinson Pressure Bar (SHPB) tests. The results showed that straw fibers slightly reduce slurry fluidity. The UCS of RSCTB at a specific mix ratio was more than 50% higher than that of cemented tailings backfill (CTB) without rice straw. The dynamic unconfined compressive strength (DUCS) of RSCTB increased linearly at different strain rates. The effect of rice straw fibers on the UCS and DUCS was much smaller than that of cement content and solid mass concentration. Excessively long and abundant straw fibers are not conducive to improving the long-term impact resistance of RSCTB. Full article

The asymmetry of seismic rupture significantly dictates the intensity and spatial distribution of the radiated stress waves during mining-induced tremors, exerting a pivotal influence on the dynamic instability of roadways triggered by mining-induced tremors. In this study, a method for simulating arbitrary rupture patterns based on the theory of moment tensors is proposed. Based on the engineering context of strong seismicity-induced roadway dynamic instability at the Xinjulong coal mine, the entire process, from the excitation and propagation of seismic stress waves to the subsequent destabilization and destruction of the roadway, is reproduced. The effects of seismic source, including rupture patterns, seismic energy, fault plane angles, and the dominant frequency of stress waves, on the stability of a roadway are analyzed. Research indicates that a strong mining-induced tremor is characterized by tensile failure, with the radiated P-waves playing a predominant role in the destabilization and collapse of the roadway compared to S-waves. The P-waves exert a repetitive tensile and compressive effect on the perturbed medium, whereas S-waves contribute through compressive shear actions. The stability of a roadway is influenced by various characteristics of the seismic source. The rupture pattern of the seismic source affects the spatial distribution of stress waves. The seismic energy influences the kinetic energy transmitted to the roadway, with an increase in energy leading to a greater contribution of S-waves to roadway destruction. The fault plane angle similarly affects the propagation pattern of stress waves, particularly at 45° and 60° angles, where the maximum radiation of P-waves is directed towards the roadway, causing the most severe damage. The dominant frequency affects the attenuation of stress waves, with lower frequencies resulting in less attenuation and a higher likelihood of roadway damage. Full article

Ecosystem services are crucial for animals, plants, the planet, and human well-being. Decreasing biodiversity and environmental destruction of ecosystems will have severe consequences. Designing technologies that could support, enhance, or even replace ecosystem services is a complex task that the Manufactured Ecosystems Project team considers to be only achievable with transdisciplinarity, as it unlocks new directions for designing research and development systems. One of these directions in the project is bio-inspiration, learning from natural systems as the foundation for manufacturing ecosystem services. Using soil formation as a case study, text-mining of existing scientific literature reveals a critical gap: fewer than 1% of studies in biomimetics address soil formation technological replacement, despite the rapid global decline in natural soil formation processes. The team sketches scenarios of ecosystem collapse, identifying how bio-inspired solutions for equitable and sustainable innovation can contribute to climate adaptation. The short communication opens the discussion for collaboration and aims to initiate future research. Full article

This study investigated safety management performance in small- and medium-sized private coal mining enterprises (SMPCMEs) through an integrated application of the 24Model accident causation theory and fuzzy-set qualitative comparative analysis (fsQCA). Analyzing 40 sudden incidents (2013–2023), we examined six key factors—organizational, individual, and external dimensions—to identify nonlinear risk pathways. Results revealed four critical failure types—Internally Balanced (cultural–behavioral–environmental collapse), Safety Culture–Deficient (institutional hollowing), Cultural–External Environment (policy-implementation paradox), and External Environment–Integrated (technological-regulatory failure)—that collectively explained 83% of performance variance. Tailored strategies, including IoT-based real-time monitoring and AI-driven inspections, are proposed to transition from fragmented interventions to systemic governance. These findings provide actionable insights for enhancing safety resilience in high-risk mining sectors. 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

The shear-compression failure of key strata leads to stair-step collapse and severe mine pressure, posing significant safety risks in coal mines. Existing theories fail to account for the boundary conditions and breaking sizes of key strata, making accurate description of shear-compression failure difficult. A periodic breakage mechanics model for key strata was developed using Timoshenko Beam and Winkler Foundation Theory, incorporating transverse shear deformation. The deflection, rotation angle, bending moment, and shear force were calculated, and a shear-compression failure criterion function f(x) was derived. The main conclusions include the following: (1) shear-compression failure is influenced by the thickness–span ratio, cohesion, internal friction angle, and elastic modulus of the key strata, but not by the elastic foundation coefficient and shear modulus; (2) shear-compression failure occurs when the thickness–span ratio reaches 0.4; (3) when the internal friction angle is 25°, 30°, 35°, or 40°, shear-compression failure does not occur if cohesion exceeds 8.0, 7.5, 7.0, or 6.5 MPa, respectively, with a larger internal friction angle corresponding to a smaller critical cohesion; (4) when cohesion is 6 MPa, 8 MPa, 10 MPa, or 12 MPa, shear-compression failure does not occur if the internal friction angle exceeds 44°, 32°, 19°, or 8°, respectively, with larger cohesion correlating to a smaller critical internal friction angle; and (5) once cohesion or internal friction angle surpasses a critical value, the failure criterion approaches a constant value, preventing failure; the elastic modulus has a greater effect on shear-compression failure than the shear modulus, with higher elastic modulus increasing the likelihood of failure. Full article

In response to the complex challenges posed by gob-side entry retaining in medium-thick coal seams—specifically, severe stress concentrations and unstable surrounding rock under composite roof structures—this study presents a comprehensive field–numerical investigation centered on the 5-200 working face of the Dianping Coal Mine, China. A three-dimensional coupled stress–displacement model was developed using FLAC3D to systematically evaluate the mechanical behavior of surrounding rock under varying roof cutting configurations. The parametric study considered roof cutting heights of 6 m, 8 m, and 10 m and cutting angles of 0°, 15°, and 25°, respectively. The results indicate that a roof cutting height of 8 m combined with a 15° inclination provides optimal stress redistribution: the high-stress zone within the coal rib is displaced 2–3 m deeper into the coal body, and roof subsidence is reduced from 2500 mm (no cutting) to approximately 200–300 mm. Field measurements corroborate these findings, showing that on the return airway side with roof cutting, initial and periodic weighting intervals increased by 4.0 m and 5.5 m, respectively, while support resistance was reduced by over 12%. These changes suggest a delayed main roof collapse and decreased dynamic loading on supports, facilitating safer roadway retention. Furthermore, surface monitoring reveals that roof cutting significantly suppresses mining-induced ground deformation. Compared to conventional longwall mining at the adjacent 5-210 face, the roof cutting approach at 5-200 resulted in notably narrower (0.05–0.2 m) and shallower (0.1–0.4 m) surface cracks, reflecting effective attenuation of stress transmission through the overburden. Taken together, the proposed roof cutting and pressure relief strategy enables both stress decoupling and energy dissipation in the overlying strata, while enhancing roadway stability, reducing support demand, and mitigating surface environmental impact. This work provides quantitative validation and engineering guidance for intelligent and low-impact coal mining practices in high-stress, geologically complex settings. Full article