Search Results (653)

The heading face is one of the zones most severely affected by dust pollution in underground coal mines, and dust control becomes even more challenging during roadway excavation with continuous miners. To improve dust mitigation in environments characterized by intense dust generation, high ventilation demand, and large cross-sectional areas, this study integrates numerical simulations, laboratory experiments, and field tests to investigate the physicochemical properties of dust, airflow distribution, dust migration behavior, and a comprehensive dust control strategy combining airflow regulation, foam suppression, and dust extraction fan systems. The results show that dust dispersion patterns differ markedly between the left-side advancement and right-side advancement of the roadway; however, the wind return side of the continuous miner consistently exhibits the highest dust concentrations. The most effective purification of dust-laden airflow is achieved when the dust extraction fan delivers an airflow rate of 500 m³/min and is positioned behind the continuous miner on the return side. After optimization of foam flow rate and coverage based on the cutting head structure of the continuous miner, the dust suppression efficiency reached 78%. With coordinated optimization and on-site implementation of wall-mounted ducted airflow control, foam suppression, and dust extraction fan systems, the total dust reduction rate at the heading face reached 95.2%. These measures substantially enhance dust control effectiveness, improving mine safety and protecting worker health. The resulting reduction in dust concentration also improves visibility for underground intelligent equipment and provides practical guidance for industrial application. Full article

The deformation and failure of surrounding rock in underground roadways are governed by complex mechanical interactions and environmental factors, yet the fundamental scientific patterns behind these processes remain unclear. This lack of real-time, data-driven understanding limits the development of intelligent monitoring and prediction systems in mining engineering. To address this challenge, this study aims to establish an intelligent system for the dynamic monitoring and prediction of roadway surrounding rock deformation based on binocular vision and machine learning. An improved Semi-Global Block Matching (SGBM) algorithm is developed for real-time 3D deformation measurement, while a physical similarity model is constructed to visualize the deformation–failure evolution. The Random Forest (RF) algorithm is employed for deep deformation prediction, and its optimal parameters are determined by minimizing the mean square error. Experimental results show that the average measurement errors of the binocular vision method are 1.22 mm and 0.92 mm, outperforming total station monitoring. The gradient-enhanced Random Forest (GERF) model achieves RMSE values of 0.0164 and 0.0113, with R² values of 0.8856 and 0.8356, respectively. Compared with AdaBoost, XGBoost, and Vision Transformer models, GERF improves predictive accuracy by 7.82%, 8.68%, and 3.87%, respectively. These findings demonstrate the scientific feasibility and technical advantage of the proposed intelligent system, offering a new approach to understanding and predicting roadway deformation and failure in intelligent mining. Full article

To reduce the risk of coal mine water inrush, a dynamic escape path optimization model based on the spatio-temporal evolution of the water inrush is studied. The actual coal mine is simplified into roadway nodes and segments to meet the real-time simulation of the coal mine water inrush, where the computational cost is reduced significantly while the accuracy is acceptable. To solve the control equations of the open channel flow and full channel flow efficiently, the lattice Boltzmann method is adopted to simulate the spatio-temporal evolution of the water inrush. Different from the previous studies, the spatio-temporal evolution of the water inrush is taken into account, which is closer to the actual case. The escape speed is not static, which is affected by the water depth dynamically; meanwhile, the effect of the physical energy reduction is considered. To validate the dynamic escape path optimization model based on the spatio-temporal evolution of the coal mine water inrush, three case studies are conducted. In the first case, there is one water inrush point and one person, while in the second case, there are two water inrush points and four persons; the third case is an actual coal mine with multiple water inrush points. We defined two indicators to evaluate the risk of the escape path quantitatively; they are the window escape time and rescue priority. By conducting the dynamic programming of the escape path, the optimal escape path is selected, where the effectiveness of the dynamic escape path optimization model is validated. The present work is helpful in reducing the risk of coal mine water inrush and improving the safety of the early warning system. Full article

As a support material for mine roadways, shotcrete (SC) exhibits performance limitations in extreme deep-mining environments characterized by high stress and water seepage. Polyoxymethylene (POM) fiber, with its properties of high strength, high modulus, and corrosion resistance, holds potential for application in surrounding rock support of deep roadways. To investigate the effect of POM fiber on the flexural performance of shotcrete, four-point bending tests were conducted on fiber-reinforced concrete specimens with different fiber lengths and dosages. Combined with ABAQUS numerical simulation, damage simulation analysis was performed on each group of specimens, and the stress propagation state of the fibers was tracked. The results show that the flexural strength of polyoxymethylene fiber shotcrete (PFS) increases with the increase in fiber length and dosage, and the influence of fiber dosage is more significant. POM fiber can effectively inhibit the crack development of shotcrete, enhancing its crack resistance and residual strength. The load-deflection curves indicate that PFS exhibits excellent fracture toughness, with the P9L42 group showing the highest flexural strength improvement, reaching an increase of 94%. The numerical simulation results are in good agreement with the experimental conditions, accurately reflecting the damage state and load-deflection response of each group of concrete specimens. Based on the above research, POM fiber is more conducive to meeting the stability requirements of roadway surrounding rock support, providing a scientific basis for the application of PFS in mine roadway surrounding rock support. Full article

In deep coal mines characterized by high temperature, high humidity, high-salinity water, and elevated ground stress, stress corrosion cracking (SCC) of bolts is widespread, causing frequent instability of roadway surrounding rock and hindering long-term stability. This study systematically examines the failure characteristics of anchorage materials in highly corrosive roadways and clarifies the effects of deep-mine temperature and humidity on material corrosion. Long-term corrosion tests on bolts reveal changes in mechanical properties and macroscopic morphology and elucidate the intrinsic mechanisms of SCC. The results show that with the increase in corrosion time, the yield strength, ultimate load and elongation of the anchor rod decrease by up to 11.8%, 13.6%, and 7.08%, respectively. Under high stress, localized corrosion pits form on bolt surfaces, rupturing the oxide film and initiating rapid anodic dissolution and cathodic hydrogen evolution. Interaction between corroded surfaces and microcracks produced by internal impurities leads to progressive damage accumulation and ultimate fracture of the bolts. These findings provide guidance for corrosion protection of coal mine roadway support materials and for improving the long-term performance of roadway supports. Full article

Deep soft rock roadways at about 1 km depth experience significant deformation due to concentrated stress ahead of the working face and dynamic loads from the hard roof layer. We propose an integrated control method that couples directional roof cutting, which interrupts stress transfer with constant resistance, and large deformation cable reinforcement to accommodate residual movement. The calibrated FLAC3D model indicates a lower front of face stress and a diminished cyclic build up of elastic strain energy in the roof, which reduces roadway convergence. Field data from Face 13403 corroborate the method’s effectiveness: the average hydraulic support load on the roof cutting side was 20.3 MPa, which is 30.1% lower than on the non-cutting side; deformation stabilized about 320 m behind the face; the final roof to floor and rib to rib closures were 1.10 m and 1.47 m; and the entry remained fit for the next panel. These results indicate that coupling roof cutting with constant resistance cable reinforcement reduces mining-induced loads while increasing deformation tolerance, providing a practical solution for stabilizing kilometer-deep soft rock roadways. Full article

To optimize the support performance of rock bolts in high-stress environments, this study employs the ANSYS (Version 2022 R2) finite element numerical simulation method to systematically investigate the influence of bolt geometrical parameters (rib spacing, rib height, and bolt diameter) on the stress state of the anchoring system. A bolt–resin–sleeve model was established to analyze Mises equivalent stress distribution and peaks under a 150 kN pull-out load. The simulation results indicate that a rib spacing of 36 mm effectively promotes the diffusion of pre-stress into deeper regions, with peak stress in the bolt rod and resin ring increasing by 34.42% and 61.64%, respectively, compared to a spacing of 12 mm. Further increase in rib spacing provides limited enhancement in peak stress. A rib height of 1.0 mm achieves optimal system performance without excessively compromising the interfacial stress level. Increasing the diameter to 22 mm raised peak stress in the bolt, sleeve, and resin by 14.19%, 30.48%, and 50.77%, respectively, compared to 18 mm, balancing load capacity and material use efficiently. The optimal parameter set (36 mm spacing, 1.0 mm height, and 22 mm diameter) was validated in a field trial in Zhongmacun Mine’s 3903 East Transportation Bottom Drainage Roadway. Monitoring recorded maximum roof subsidence of 102.9 mm, stabilizing within 25 days (daily deformation < 0.2 mm), confirming the excellent performance of the bolt support system with this parameter combination in high-stress roadways. This study provides a theoretical basis and engineering reference for the optimal design of high-performance rock bolts. Full article

Sustainable mine geothermal energy causes high-temperature hazards in mine roadways, severely endangering miners’ lives. There is an urgent need to enhance research on the performance of composite phase change material (CPCM) roadway cooling systems, as they can effectively control ambient temperatures. However, existing research on CPCM roadway cooling system performance remains limited. This study innovatively establishes a numerical model for a novel cascade CPCM roadway cooling system and employs the control variable method to investigate the influence of multi-parameter regulation on system performance. The study reveals that the ring pipe radius ratio significantly impacts the system’s heat exchange efficiency and temperature distribution. The optimal comprehensive system performance is achieved at an annular tube radius ratio of 2:3, where the CPCM solid phase percentage for 89.03% and the average temperature of the monitoring surface decreases by 9.54 °C. Increasing the cascaded tube spacing enhances the overall cooling effect, but cooling efficiency diminishes when the spacing exceeds 0.5 m. The CPCM phase change temperature must align with the mine’s geothermal conditions, with CPCM utilization and cooling efficiency peaking at 25 °C. The air deflector structure effectively mitigates cooling lag in the lower roadway section. At an installation angle of 30°, the expansion distance of the lower low-temperature zone increased by up to 48.89% without compromising cooling efficiency in the upper roadway section, while also delaying the recovery rate of heat damage. Full article

This paper presents a hybrid methodology for predicting rock mass deformation and roadway loads induced by longwall mining. The approach combines the classical Budryk–Knothe influence function model with numerical simulations in the FLAC3D finite difference environment. Instead of explicitly reproducing large-scale excavation and caving, the impact of mining is introduced through analytically derived displacement boundary conditions applied to the numerical model. This allows detailed analyses of the rock mass deformation state while significantly reducing computational effort compared with conventional geomechanical models. The methodology involves deriving displacement components from the Budryk–Knothe influence function, implementing them through Python 3.6.1 scripts in FLAC3D 7.00, and performing stepwise simulations of longwall advance. Results show that the proposed approach reduces the number of finite difference zones by nearly an order of magnitude, achieving more than a tenfold decrease in computation time. At the same time, the displacement and stress distributions obtained remain consistent with both the analytical Budryk–Knothe solution and those from the classical numerical model. The study demonstrates that this methodology provides a reliable and efficient tool for assessing stress redistribution and deformation around roadway excavations influenced by mining. Its application enhances the accuracy of deformation predictions, supports support system design, and improves safety and efficiency in underground mining operations. Full article

The performance of resin anchoring agents in deep coal mine roadways is significantly compromised by water-bearing and chemically aggressive conditions, posing a major threat to support system reliability. This study aims to systematically quantify this performance deterioration and develop a more resilient material solution for these challenging environments. A comprehensive experimental program was conducted, including uniaxial compression, pull-out, and interface shear tests, accompanied by the systematic improvement of the resin formulation and microstructural analysis via Scanning Electron Microscopy (SEM). The results showed that increasing borehole water content to 30% reduced the compressive strength of conventional resin by over 40%, while acidic environments (pH = 5) caused a 70% drop in its interfacial shear strength. In contrast, an improved formulation incorporating hydroxypropyl acrylate and a super absorbent polymer (SAP) exhibited a 20% higher initial strength, maintained over 85% of its strength under water saturation, and retained functional residual strength in acidic conditions. SEM analysis confirmed that the improved resin’s denser microstructure suppressed interfacial microcrack formation. The findings demonstrate that the improved formulation provides a robust material basis for enhancing the long-term durability and safety of anchorage support systems in extreme underground engineering environments. Full article

This article presents a concept for modernizing the transport system of high-performance coal mines through the transition from traditional monorail to rubber-tyred transport (RTT). The study was conducted based on materials from the V.D. Yalevsky Mine of JSC “SUEK-Kuzbass” with daily longwall output up to 60,000 tons and production capacity up to 10 million tons per year. Analysis of the existing transport system efficiency revealed low equipment utilization rates (52–70%) and significant time losses during shift changeovers (up to 4.3 h/day in development workings). Technical solutions for phased RTT implementation were developed, including six roadway surface scenarios and a fleet composition of 60 specialized equipment units. The research methodology is based on time study observations using the automated “Granch” system, analysis of equipment utilization coefficients, and economic–mathematical modeling using NPV, MIRR, and payback period. The transition to rubber-tyred transport provides a five-fold increase in travel speed (from 4.5 to 25 km/h), reduction in shift changeover time to zero, increase in operating time by 20% in development and 4.5% in extraction, and a reduction in longwall move duration from 173–209 to 88 days. Additional coal production amounts to 6.5 million tons. Economic justification shows NPV of USD 64.2 million with MIRR of 2.4% and a payback period of 4.5 years. Full article

After water gushing occurs in a coal mine roadway, abundant aggregate needs to be perfused into the water gush roadway to establish a water interception section and reduce the current velocity. Clarifying the water-intercepting aggregate motion path and quantitatively calculating the displacement distance are critical for determining perfusion hole spacing. This paper employs the CFD-DEM coupling approach, which is capable of accurately characterizing the water gush continuous flow properties and the aggregate discrete motion behavior. This can be used to simulate and analyze the water-intercepting aggregate motion in a water gush roadway, categorizing it into three phases: free fall, curvilinear projectile, and sliding. The theoretical motion model aggregate can be developed, and the calculation formulas for aggregate motion distances in each phase derived. A parameter test scheme was designed and combined with numerical simulation methods to verify the accuracy of the formulas. Finally, based on this research, it is proposed that the theoretical model can be used to dynamically optimize the design of perfusion hole spacing, maximizing the synergistic effect of multi-hole perfusion. The selection of aggregate density and size should ensure the vector sum of the aggregate motion distance in phase II and III approaches zero, thereby improving the water-intercepting efficiency. Full article

When excavating roadways in underground mines, stress redistribution within the surrounding rock mass leads to stress concentration and release. Should the concentrated stresses exceed the rock mass’s tensile or shear strength, rock deformation and failure occur. Thus, a knowledge of stress distribution around the roadway is of great significance for revealing the roadway instability mechanism and design support methods. In this work, the powerful complex variable function theory was used to solve the surrounding rock stress around the triple-arched roadway and the analytical results were verified with the on-site stress state. The results show that the tensile stress occurs on the roadway roof and floor under low lateral stress coefficients, while concentrated compressive stress emerges on the two sidewalls. However, the surrounding stress distribution exhibits an opposite characteristic under high stress levels. Beyond five times the roadway radius, the stress in the surrounding rock is unaffected by the roadway and approaches the in-situ stress. For the +1890 m level trackless transport roadway in Kunyang No. 2 phosphate mine, it is further calculated that the minimum stress concentration factor in the rib area of the roadway within the stress relief zone is 0.34, while the maximum stress concentration factor in the concentrated stress zone of the roof, floor, and sidewalls of the roadway is 5.87. The measured stress values of two monitoring points in the surrounding rock of this roadway are fairly consistent with the analytical values, suggesting the complex variable method for solving excavation-induced stresses are effective and reliable. Full article

In underground mine roadways, enlarged cross-sections have led to escalating surrounding rock stress, resulting in frequent support failures, elevated accident risk, and increased maintenance costs. However, the potential of fiber reinforcement to improve shotcrete under these high-stress conditions remains under-investigated. To address these issues, this study developed a novel fiber-reinforced cement-based composite using field construction-grade washed sand. The effects of binder-to-material ratios, fiber types (polyvinyl alcohol (PVA), polypropylene (PP), and basalt (BF)), and fiber dosages (1%, 2%, and 3%) were systematically investigated under uniaxial tension, uniaxial compression, and variable-angle shear. Based on the experimental results, an optimal mix formulation was determined via orthogonal experimental design to meet mining operational requirements. The findings demonstrate that fiber incorporation significantly enhances mechanical performance. Notably, PP fiber reinforcement increased the tensile strength by up to 675%, while BF fibers improved compressive strength by up to 198.5%, relative to unreinforced shotcrete. This study provides a theoretical foundation for optimizing fiber-reinforced shotcrete mix designs for mining and offers technical insights for field applications. Full article

Coal pillars are important safety structures for maintaining the stability of underground coal mine roadways. To address both coal resource loss from wide pillars and the need for safer, more sustainable underground building structures, this study proposes a framework for controlling the surrounding rock based on the narrow pillar. By establishing a load-bearing mechanical model for narrow coal pillars and a mechanical model for roof instability, the design principles of key parameters were clarified, including the optimal width, the required support strength for the pillar–roof system, and the height and angle of roof pre-splitting. In addition, zoning control measures and corresponding technical procedures for adjacent mining roadways were proposed. This technology was applied in Tashan Mine and, during the extraction of panel 8311, the surrounding rock stability of roadway 2312 was well maintained, with the maximum deformation of the solid coal rib measured at 135 mm, while that of the narrow pillar reached 386 mm. The proposed design method can effectively improve coal recovery in underground mining and provide theoretical and technical guidance for coal pillar stability control and wide pillar optimization under complex mining conditions. Full article