With the global energy system undergoing a low-carbon transformation and China’s high-quality development strategy advancing in depth, coal mine design and construction are shifting from a focus on “high capacity” to “high quality, safety, intelligence, greenness, and sustainability.” Based on a systematic review of the evolution of coal mine design concepts in China and drawing upon more than seventy years of design experience from CCTEG Wuhan Design and Research Institute Co., Ltd., this study innovatively proposes the “6S” top-level design principle for modern coal mine engineering. Guided by top-level system thinking, the 6S framework emphasizes the integration of technology, economy, and ecology, and further establishes the coupling pathway between the 6S principles and the “ICIE” features of next-generation intelligent mines—Intelligent sensing, Carbon-low integration, Intrinsic safety, and Ecological harmony—forming a forward-looking paradigm for future coal mine construction. Through engineering practice analyses of two representative projects, Caojiatan Coal Mine and Xinjie No.1 Mine, the study verifies the remarkable effectiveness of the 6S concept in enhancing safety performance, optimizing systems, controlling investment, and advancing green and low-carbon development, thereby providing theoretical guidance and engineering demonstration for the high-quality development of the coal industry.

Against the backdrop of the global energy transition, the intelligent development of coal mining exhibits diverse pathways. This study constructs a three-dimensional analytical framework encompassing "geological constraints, technological pathways, and policy drivers" to conduct an in-depth comparative analysis of intelligent mining models in China and Australia. The results reveal that Australia, leveraging its resource endowment and market mechanisms, has developed an enterprise-led "natural evolution model" centered on efficiency. Conversely, China, under the dual constraints of complex geology and energy security strategy, has established a policy-driven "top-down design model" prioritizing safety. Resource endowment serves as the initial determinant of pathway selection, while policy and market mechanisms act as the key drivers shaping the model's final form. Together, they determine the path dependency and evolutionary trajectory of intelligent mining development. The research highlights significant complementarity between the two countries in areas such as complex geological mining, intelligent disaster prevention and control, and equipment standardization. It further proposes synergistic pathways, including collaborative technical standard development, scenario-based integration, and internationalization of research outcomes. The findings provide a dual-track complementary paradigm integrating "resource endowment adaptability" and "policy-driven effectiveness" for the global coal industry's intelligent transformation. This research holds both theoretical and practical significance for China's efforts in building a new energy system.

This study aims to address the issues of large drilling volume, poor extraction effect, and long compliance time of traditional anti outburst methods when exposing high outburst coal seams from a small angle. By implementing a regional gas control model of gas extraction assisted roadway and mechanical hole making for enhanced permeability in newly built coal mines, an innovative and rapid gas outburst reduction technology path has been proposed. The research content includes auxiliary extraction roadway design, drilling layout, and mechanical hole construction technology, and a detailed analysis of their effects. The on-site application results show that this technology significantly reduces the amount of drilling work (reducing 11544m), improves gas extraction efficiency (increasing the average purity by more than three times), and shortens the regional outburst time (shortening 78 days). Comprehensive cost analysis shows that it can save 387000 yuan in costs compared to traditional methods. This study not only provides a safe and fast technical path for small angle coal mining faces to eliminate outbursts, but also has important significance for ensuring the overall safety and efficient production of mines.

In response to the issue of the east and west boundaries of the first mining area of the Hongshaquan open-pit mine being bent due to the location of the screening plant, when the screening plant is about to be dismantled, the west boundary is about to reach the limit, and the waste rock dumping line will cover the "U"-shaped bend of the east boundary, the length of the working line of the first mining area after the dismantling of the screening plant was optimized. The economic and reasonable working line length and the technically feasible working line length were calculated respectively by theoretical calculation and model verification methods. It was concluded that the working line length of the open-pit coal mine under the target production capacity is about 2800 m, and the feasibility was verified through engineering position deduction. Based on the actual situation of the Hongshaquan open-pit mine, a relationship model of the in-pit dumping method within the pressure bank based on the minimum total cost was constructed, and the secondary stripping and transfer-dumping costs under different pressure bank heights were calculated. The research shows that as the pressure bank height increases continuously, the total cost of the pressure bank also increases continuously. Based on the principle of minimizing the total cost of the pressure bank, the full pressure bank in-pit dumping method was finally determined.

Abstract：The control indicators for construction land of industrial projects are of great significance for the economical and intensive use of land. This paper systematically reviews the 2004, 2008, and 2023 versions of the "Control Indicators for Construction Land of Industrial Projects" promulgated at the national level, summarizes the changes in the indicator system, core parameters, etc., and also elaborates on the control indicator systems and specific requirements promulgated by local departments. It systematically explains the particularities of industries such as coal in terms of pipelines, land use layout, and work safety, as well as the problems existing in the application of the "Control Indicators for Construction Land of Industrial Projects" during the review by urban planning departments and experts. Based on personal work experience, relevant suggestions are put forward.

According to the characteristics of fissure development and strong water yield in the aquifer of bedrock weathering zone overlying S1234 working face in Ningtiaota Coal Mine, based on the theory of elasticity and Bingham rheological equation, the calculation model of horizontal directional grouting borehole stress field and the grouting diffusion model of bedrock weathering zone aquifer are constructed. Considering the influence of horizontal directional drilling stress field and slurry diffusion characteristics, the calculation formula of grouting pressure in the aquifer fissure of bedrock weathering zone is proposed. According to the strength parameters and fracture development characteristics of the weathered bedrock layer, the grouting pressure is determined to be 8.4MPa, taking the 30m thick weathered bedrock layer as the effective diffusion radius of the slurry. Through the rational design of slurry ratio and grouting rate, the effective diffusion of slurry in the bedrock weathering zone aquifer fissure channel is realized. Finally, horizontal hole drilling and underground water drainage test were used to verify the water plugging effect of on-site grouting. The results show that the underground water inflow is reduced from 128m3/h before grouting to 13.8m3/h, and the water plugging effect of roof weathering zone is significant, which provides a reference for water disaster treatment of bedrock weathering zone under similar engineering conditions.

In the Liupan area of Changping Mine, the surrounding rock in the main roadway suffered severe deformation (fragmentation) under the influence of superimposed stress. The simple use of anchor cables for support was ineffective. Therefore, this paper adopted the technology of grouting reinforcement and anchor cable support to control the deformation of the surrounding rock. The UDEC software was used to simulate the diffusion law of the slurry and the reinforcement effect, and FLAC3D was employed to further analyze the manifestation of mine pressure in the main roadway after the grouting and anchoring. The UDEC simulation results showed that as the water-cement ratio and the injection pressure increased, the diffusion radius of the slurry also increased. The water-cement ratio of the slurry should not be less than 0.7:1, and the injection pressure should be greater than 4 MPa. Grouting reinforcement enhanced the anchoring force of the fractured surrounding rock, significantly reduced the range of plastic zone in the roadway surrounding rock and the displacement of the roadway. The FLAC simulation showed that after conducting grouting in the main roadway and then implementing anchor cable support, the deformation of the roadway was significantly reduced. After grouting reinforcement, the southwest auxiliary transportation roadway, which was most affected by the superimposed stress, had a top and bottom plate displacement of 69.73 mm, and the side wall displacement was 67.46 mm. The grouting anchoring support technology had achieved the stability of the roadway, providing certain reference value for the stability of the surrounding rock of similar working conditions' roadways.

Regarding the problem of deformation and instability of the surrounding rock of the roadway during the passage through the empty roadway during the advancement process of the 12404 working face of Shangwan Coal Mine, numerical simulation and field testing methods were used to deeply study the stress and displacement response characteristics of the surrounding rock and their dynamic evolution laws of the goaf at different advance distances during the working face advancement process. The deformation characteristics and stability differences of the surrounding rock before and after the advance goaf support were compared and analyzed in detail. The results show that as the working face approaches the goaf, the surrounding rock of the roadway is significantly disturbed by mining, especially within a range of 20 meters from the goaf. Instability phenomena such as roof collapse, floor bulging, and coal caving are significantly intensified, and local stress concentration forms a high peak area. The maximum roof settlement reaches 1.8 meters, and the horizontal displacement of the coal caving reaches 376 mm. The risk of collapse of the goaf and subsequent instability of the advancing coal pillar increases. After the implementation of pillar support in the advanced goaf, the overall stress field of the surrounding rock tends to be uniform, and the high stress concentration of the roof, support and bottom rock layers is effectively weakened. The peak stress is generally reduced by 3-5 MPa, and the roof subsidence, pillar deformation and support failure are significantly reduced. The internal support columns of the advanced goaf not only bear vertical loads, but also achieve peak shaving and diffusion of surrounding rock stress, improving the mechanical stability of the surrounding rock structure and enhancing the stability of the roadway in complex stress environments. The research in this paper has important guiding significance and engineering reference value for the optimization of goaf support and safe mining under similar conditions.

Exploration-production imbalance has long been a core bottleneck to safe, efficient, and intelligent coal mining in China. This study employs Seismic-while-excavating (SWE) technology for dynamic fault monitoring within the working face. First, adaptive filtering, empirical mode decomposition (EMD), and time-window segmentation preprocess vibration signals from the road header collected by the geophone array. Then, using an SWE interferometry imaging method, long-term continuous seismic signals measured in the roadway are cross-correlated with concurrent near-source wavelet signals from the road header. By leveraging principles of artificial controlled sources, this process generates virtual shot gathers resembling conventional seismic data. Finally, dynamic seismic imaging technology utilizes these equivalent shot gathers and precise road header positioning to detect geological structures within the working face. Predicted results align closely with actual conditions, confirming this technology enables refined dynamic monitoring of internal faults.

Blasting engineering, as the front link of most open pit mining, is the basis to ensure the safe and efficient operation of the subsequent open pit mining production links, such as mining, transportation and discharge. With the development trend of intelligent upgrading and transformation of open-pit mines, the information design of blasting production and the fine control of blasting construction have attracted more and more attention from the industry. In the process of blasting in open-pit mines, the determination of explosive initiation time is very important to the implementation of supervision of blasting safety production and the study and judgment of blasting seismic grade with relevant national departments such as emergency Management Bureau, mine safety Supervision Bureau and earthquake Bureau. However, in the past open-pit mine blasting practice, the initiation time is often only judged by experience, and the time recording unit is generally only up to the second level or classification, and the time recording is relatively rough. However, with the popularization and application of information technology and intelligent technology, it provides the possibility to realize the accurate collection and fine analysis of blasting production information. Therefore, in order to scientifically and accurately quantify the initiation time of blasting engineering, assistant relevant departments to supervise the production safety of blasting engineering. Firstly, the difficulties and pain points of recording the initiation time of engineering blasting are systematically expounded, and the method of confirming the initiation time of explosives based on surface detonator blasting is proposed. Secondly, based on modern high technology such as information technology and intelligence, a method of acquisition of explosive initiation time based on high-speed photography technology is proposed to solve the bottleneck problem that it is difficult to accurately collect the changing state of explosive after detonation. Finally, based on image recognition and wavelet transform technology, a set of automatic image analysis and image processing methods are proposed. The results show that this automatic image processing method can be accurate to millisecond key frame time, and the identification error of the characteristic image of the explosion area can be effectively controlled at 0.1%. The research results can provide basis and reference for the design and optimization of blasting parameters in open pit mining industry.

The mining of isolated island working face under deep cover with overlying hard strata is prone to severe strata pressure behavior, threatening coal mine safety. This study, based on the 3206 isolated island working face at Shanxi Tiandi Wangpo Coal Mine, employs a combined methodology of theoretical analysis, numerical model-ing, and field measurement. A mechanical model of the coal-rock mass loading before and after mining was established. The deformation characteristics and stress transfer evolution laws before and after the weakening of the hard strata were comparatively analyzed, and the effectiveness of hydraulic fracturing treatment was val-idated through field measurements. The results indicate that the isolated panel is subjected to a high static load from its self-weight and the transferred load from the adjacent goafs on both sides, superimposed by a dynamic load equivalent to twice the static load step variation before and after the fracturing of the hard strata, leading to a high dynamic response in the stope. When the panel advanced into the initial fracturing zone after strata weakening, the extent and degree of strata failure were limited, and the pre-splitting effect was not significant. Upon advancing into the fully fractured zone, the overall plastic failure range of the strata increased, the failure modes diversified, and the failure intensity deepened. The vertical displacement at the working face rapidly increased to 5.31 m. A larger tensile stress zone developed in the roof above the goaf, while the stress concen-tration in the front coal body decreased to 24.4 MPa, a reduction of 3.17% compared to the pre-weakening condition. The stress concentration zone shifted forward into the rock mass. As mining progressed, the front hard strata broke and caved in a timely manner, preventing large area

High-intensity fully mechanized top coal caving mining in extra-thick coal seams is prone to inducing compound disasters, including strong strata behaviors at the working face and surface collapse. To investigate the spatiotemporal correlation between these phenomena, this study takes the F6204 working face in Bulian'gou Coal Mine as a case study. By integrating field measurements and PFC discrete element numerical simulations, the intrinsic relationships between the two phenomena in terms of time, space, and evolutionary processes were systematically analyzed. The results indicate a significant spatiotemporal synergy between surface collapse and strong strata behaviors: temporally, surface collapse lags behind strong strata behaviors by approximately 2–3 days; spatially, both phenomena occur near the square-position of the working face advancement; in terms of evolution, surface collapse characteristics develop rapidly after the occurrence of strong strata behaviors. Furthermore, this study reveals the linkage mechanism between “strong strata behaviors underground and surface collapse aboveground.” The rupture and instability of the hard basalt main key stratum integrate the two phenomena. Its failure triggers chain instability in the underlying strata, leading to an instantaneous increase in support resistance and the upward transmission of ultra-large separation space, ultimately inducing surface collapse. This research provides theoretical and practical insights for ecological protection and disaster prevention in surface environments during extra-thick coal seam mining.

In order to solve the problem of controlling roof shear-induced subsidence and surrounding rock stability during gob-side entry retention in shallow, medium-close distance coal seams, this study investigates the 42305 working face of Wanli No. 1 Mine. Based on borehole imaging results and analysis of the overlying strata structure, the primary causes of extensive roof weighting and shear-induced subsidence along the rib were identified. Accordingly, a structural mechanical model for gob-side entry retention in shallow, medium-close distance coal seams and a simplified rock beam mechanical model for the interlayer key stratum were developed. Theoretical calculations determined that the maximum bending moment and shear force in the overlying strata of the retained entry are 14773.5 kN·m and 6009.58 kN, respectively. Analysis of the overlying strata structure and rock mechanical properties indicates that failure primarily occurs in the shallow weak rock layers. Therefore, a combined strategy of "grouting reinforcement" and "U-shaped steel sets with anchor cable suspension beams" was proposed to enhance the existing support system. These measures improved the shear resistance of the shallow weak rock layers to 6111.68 kN. Field monitoring results demonstrated a significant reduction in the roof subsidence rate, with a maximum stabilized subsidence of 195 mm, confirming effective control of the shear-induced subsidence. This study offers a practical reference for managing roof shear-induced subsidence and surrounding rock stability in gob-side entry retention under similar engineering and geological conditions.

Aiming at the key technical challenges such as poor borehole cleaning and unstable borehole wall in gas drilling under water-inrush conditions in broken-soft coal seam in underground coal mine, an in-depth analysis of the drilling debris transport process under water-inrush condition was conducted. The study revealed the mechanism by which water inrush in the strata leads to annular blockage and drilling resistance. Based on this, key technologies for air directional drilling suitable for water-inrush conditions in the strata were developed, and supporting drilling equipment was optimized and integrated. Field industrial tests were also conducted. The results showed that: (1) The dynamic imbalance of "gas-liquid-solid" multiphase flow in the borehole annulus leads to a sharp decline in annular debris removal efficiency and energy loss in gas circulation, which is the main cause of resistance to air directional drilling. Its prominent manifestations include a surge in debris removal resistance, an increase in annular pressure drop gradient, and even severe annular blockage. (2) A method for collaborative identification of water inrush in the strata based on comprehensive exploration technology was proposed, providing a basis for optimizing the design of borehole trajectory. By integrating real-time monitoring data such as drilling parameters, air supply parameters, and water inflow from the strata, a criterion for identifying precursor characteristics of borehole blockage was established. A composite debris removal technology based on feedback from monitoring parameters was developed, effectively reducing the adhesion of drilling debris to the drilling tools and borehole walls and improving debris removal efficiency. (3) Using a complete set of technical equipment, 7 directional boreholes were successfully drilled under local water-inrush conditions in a broken-soft coal seam in Huayang Second Mine in Shanxi Province, including five boreholes over 350 meters deep, with the maximum borehole depth reaching 506 meters, achieving significant gas extraction results. The research findings provide important technical references for gas extraction in broken-soft coal seam under similar geological conditions and have promotion and application value.

The intelligentization of coal mines is the core technological support for the high-quality development of the coal industry, and also an important component of cultivating new quality productivity in the coal industry. The coal industry has promoted the rapid development of intelligent construction in coal mines through measures such as promoting mechanism guarantees, collaborative research and development of technology and equipment, and demonstration coal mine construction. The results of reducing personnel, increasing safety, and improving quality and efficiency are significant. This article summarizes and analyzes the development achievements of intelligent construction in China's coal mines and the problems existing in normalized operation and maintenance management. Based on a comprehensive summary of the construction and operation of the unmanned system in Baode Coal Mine, the existing problems are proposed. A management model based on human-machine material management and PDCA was proposed, and combined with the establishment and management practice of Baode Coal Mine's intelligent operation and maintenance management organization, the implementation effect of Baode Coal Mine in safety production, production efficiency, and achievement control was verified, providing an example and reference for the industry's intelligent operation and maintenance.

Employing an integrated methodology of theoretical analysis, numerical simulation, and coupled monitoring, this study conducted a systematic investigation into the deformation and instability mechanism of surrounding rock in gob-side entry driving under hard roof conditions, using the 21407 longwall panel of a specific coal mine as its research background. A mechanical structure model for the entry with a hard immediate roof under static-dynamic coupling loads was established to analyze the impact of both the gob-side cantilever beam structure and the hard arc triangular zone structure at the panel end on surrounding rock deformation. An innovative three-dimensional surrounding rock monitoring technology system was developed, which utilizes 3D laser scanning for dynamic deformation capture and integrates distributed bolt (cable) stress monitoring to form a coupled "deformation-stress" monitoring system, enabling a quantitative analysis of the full-lifecycle deformation laws of the surrounding rock. The results demonstrate that the surrounding rock is significantly influenced not only by the static load from the gob-side cantilever beam but also by the dynamic pressure originating from the hanging roof at the working face end. The deformation exhibits spatiotemporal evolution characteristics across five distinct phases: the driving influence period, stable creep period, long-term rheological period, mining influence period, and strong disturbance influence period. Integration of theoretical analysis and CDEM numerical simulation results revealed the deformation and instability laws, indicating a positive correlation between floor heave and roof subsidence, greater deformation on the small coal pillar side compared to the solid coal side, and a periodic pattern of asymmetric and alternately evolving deformation on both sides. The superimposed effect of static and dynamic loads forms a synergistic force source system, providing novel perspectives and ideas for innovating the deformation theory of surrounding rock in such conditions and offering a more scientific basis for determining optimal support timing.

In deep buried roadways, the advanced section often experiences rock fragmentation and crack development due to mining activities, leading to significant deformation and potential instability, which seriously threatens underground safety. To investigate the failure and deformation behavior of such roadways, this study takes the 13207 belt entry in Wuju Coal Mine as a case study. Loose circle detection was conducted, followed by the establishment of a numerical model to analyze the zoning of the advanced section under abutment stress. The stress distribution and failure characteristics of the roadway were revealed. Targeted zoning support designs were proposed and validated through field monitoring data. Key findings include: (1) Based on stress distribution, the area within 10 m ahead of the working face is identified as the stress concentration zone, 10–27.5 m as the stress decay zone, and beyond 27.5 m as the original rock stress zone; (2) The stress concentration zone exhibits the most severe deformation, particularly at the ribs. When the face advanced 200 m, rib deformation reached 843.27 mm, which is 3.17 times the roof subsidence and 2.42 times the floor heave; (3) Plastic failure is pronounced at the ribs, with the plastic zone gradually decreasing with increasing distance from the face; (4) A "three-beam three-column" support method was applied in the stress concentration zone. Monitoring showed that surrounding rock deformation decreased by over 40% after reinforcement, demonstrating the effectiveness of the support design.

This study characterizes the instability characteristics (e.g., deformation and failure) of roadway surrounding rock induced by repeated mining in close-distance coal seams. A dynamic model for repeated mining was established based on the force equilibrium principle, yielding a novel surrounding rock instability criterion. The deformation-failure laws and mechanical behavior of the surrounding rock under repeated mining were systematically investigated using 3DEC discrete element numerical simulation. Integrating these findings with field monitoring data, targeted stability control measures and an implementation scheme were developed. Key results demonstrate that: The proposed instability criterion index effectively characterizes failure modes under repeated mining; Instability occurs when the index > 0, while stability is maintained at values ≤ 0; Increasing the staggered distance between gate roadways in the upper and lower seams mitigates the influence scope of mining-induced roadway displacement and overlying interburden disturbance; Implementation of a staggered roadway layout combined with an intensive support scheme reduces post-support surrounding rock stress by 22.5%. These findings provide a theoretical basis and practical guidance for stability control in similar repeated mining engineering contexts.

Aiming at the problems of unclear load transfer mechanism of overburden rock under the influence of mining and difficult to quantitatively characterise the lateral support pressure distribution, this paper establishes a hypothetical cantilever beam mechanical model of elastic foundation based on the assumption of Winkler's elastic foundation according to the spatial structural characteristics of the peripheral rock of the quarry after the coal seam mining, and adopts the Rayleigh-Ritz method to derive the distribution equations of the lateral support pressure on the coal body under the action of the overburden rock's centralised load in the mining area, and verifies the theoretical model by numerical simulation in the context of actual engineering. The theoretical model was validated by numerical simulation with the background of actual engineering. Through the model verification and parameter analysis, the results show that: (1) the support coefficient c in the model parameters does not affect the support pressure value, but has a greater impact on the vertical displacement of the lateral coal body, and the vertical displacement decreases with the increase of the support coefficient c. The support pressure value is mainly related to the mining influence range l and the value of mining overburden load F, in which the mining overburden load F and the depth of the coal seam are positively correlated, and the deeper the depth of the coal seam is, the higher the support pressure value increases, and the mining influence range l increases, and the mining influence range F increases, and the mining influence range l increases. The larger the burial depth is, the value of bearing pressure increases, and the value of mining influence range l mainly affects the distribution of bearing pressure; (2) the field measurement and numerical simulation show that the mechanical model calculation results and the measured data in the elastic deformation zone are highly consistent, indicating that the model established in this paper can better reflect the vertical deformation of the lateral coal body under the action of overburden load in the mining hollow zone, as well as its distribution of the bearing pressure within the elastic deformation range. This paper provides a theoretical basis for the study of overburden load transfer and working face peripheral rock deformation under the influence of mining, which is of great significance in guiding the safe mining in the mining area

To determine the optimal stemming length for hard rock weakening in underground coal mines, this study investigates the motion law of the stemming structure. Using LS-DYNA, the movement of the stemming structure under both rigid piston compression and explosive blasting was simulated. The results reveal non-uniform compression within the borehole, with maximum density at the compression end and minimum at the free end, followed by rigid-body motion post-compression. Based on these characteristics, a one-dimensional axial motion mechanical model was established. The calculation of explosion gas pressure was systematically improved by considering its attenuation due to rock failure, stemming compression, and movement. A "time-segmented" solution method was applied to analyze the stemming motion process, and a corresponding algorithm was designed. Finally, the method was validated in a hard rock deep hole weakening project at a coal mine heading face.

The spiral drum of the coal shearer generates instantaneous alternating impact loads when cutting coal and rock layers, causing the drum to vibrate in all directions. The vibration state varies with different cutting conditions. It is difficult to effectively perceive the current cutting state by extracting only a single vibration feature. This paper proposes a coal-rock cutting state perception system based on D-S fusion. Both the cutting force and the two front-end vibration signals are collected as features, and the corresponding transformed feature vectors are input into the RBF neural network. First, the recognition result of a single signal is obtained, and then the D-S fusion based on the evidence correlation coefficient is carried out at the decision-making level. This scheme can increase the average recognition accuracy rate to 96.5%.

To effectively predict the severity of mine water hazards and enhance coal mine water disaster prevention, a GRA-GT combination weighting evaluation model was proposed based on Grey Relational Analysis (GRA) and Game Theory (GT). This model employs GRA to quantify the relational degree between the risk of coal mine water inrush and key controlling factors, including aquifer water pressure, specific water yield, core recovery ratio, equivalent thickness of the aquiclude, thickness of brittle rock beneath the mining-induced fractured zone, fault fractal dimension, fold deformation coefficient, and density of collapse column distribution. Game Theory was then applied to optimize the subjective weights derived from the Analytic Hierarchy Process (AHP) and the objective weights obtained from the CRITIC method, constructing an optimal combination weight set. The model was applied to evaluate Roadway A, Roadway B, Roadway C, and Roadway D in Pingshuo Mine No.3. The evaluation results indicated that Roadway D had the highest water inrush risk, followed by Roadway A, while Roadway B exhibited the lowest risk. The model effectively balances subjective and objective weights, provides quantifiable and intuitive evaluation results, and demonstrates strong engineering applicability. It offers a dynamic evaluation framework integrating theoretical rigor with practical applicability for the graded management of coal mine water inrush risks.

In order to reveal the failure characteristics and mechanical mechanism of pulsed abrasive water jet impacting loaded coal rock. the corresponding numerical model is established by using Smoothed Particle Hydrodynamics-Finite Element Method ( SPH-FEM ). The temporal failure processes of coal and rock under stress-free and two-dimensional stress states impacted by pulsed water jet and pulsed abrasive water jet were compared and analyzed. The influence laws of changes in jet parameters such as pulse amplitude, pulse frequency, and abrasive mass concentration on the failure characteristics of coal and rock under two-dimensional stress were studied. The damage evolution law and stress distribution characteristics of coal rock under non-stress and two-dimensional stress state of pulsed abrasive water jet impact are revealed. The results show that compared with pulsed water jet, pulsed abrasive water jet has higher crushing efficiency, and the application of two-dimensional stress significantly inhibits the formation of crushing pits and the initiation and propagation of internal cracks in coal and rock. With the increase of pulse amplitude, the depth, cross-sectional area of the longitudinal section, and total length of main cracks of coal and rock crushing pits all gradually increase. As pulse frequency or abrasive mass concentration increases, the depth, cross-sectional area of the longitudinal section, and total length of main cracks of coal and rock crushing pits first increase and then decrease. The unit measuring points close to the coal and rock surface exhibit instantaneous damage characteristics, while those far from the surface show stepwise cumulative damage characteristics. Meanwhile, the peak effective stress of different measuring points alternates with time. The loading of two-dimensional stress increases the stress threshold of coal-rock unit failure, thus enhancing the ability of coal-rock to resist damage and failure. The research results provide theoretical guidance for the optimization of process parameters in the impact of loaded coal and rock by pulsed abrasive water jet.

Abstract: Hydraulic techniques employed in coal mines, including coal seam water infusion and hydraulic fracturing, introduce water into coal seams. The subsequent imbibition and migration of the retained water within the coal's pore-fracture system govern the final wetting state of the coal mass. Given coal's complex pore-fracture network, its micropores, mesopores, and macropores compete for the retained quantitative water. To investigate the migration behavior of quantitative water within the pore-fracture structure of bulk coal, an experimental study on its imbibition and migration was conducted. Utilizing low-field nuclear magnetic resonance (NMR) technology, the migration patterns of quantitative water within the micropores, mesopores, and macropores of bulk coal were tested and analyzed. The results demonstrate that: The migration of quantitative water in bulk coal exhibits two distinct stages. In the initial stage, the externally introduced water simultaneously enters both adsorption and seepage pores, resulting in a decrease in the free water signal and an increase in the adsorbed and bound water signals in the NMR data. During the second stage, water within the seepage pores progressively migrates into the adsorption pores driven by capillary forces, ultimately completing the transfer from seepage to adsorption pores. At the conclusion of imbibition, water wetting the adsorption pores constitutes 62% to 99% of the total, while water retained within seepage pores accounts for only 1% to 38%. The wetting rate per unit time of water within the pore-fracture structure of bulk coal shows a positive linear correlation with porosity. Well-developed pore throats enhance the coal wetting efficiency under the combined influence of capillary and gravitational forces. Conversely, the imbibition equilibrium time within the coal's pore-fracture structure exhibits a non-linear negative correlation with porosity, fitting the Boltzmann equation. By examining the imbibition and migration behavior of quantitative water in the pore-fracture structure of bulk coal, this research provides a comprehensive analysis of coal seam imbibition mechanisms and characteristic fluid migration patterns, thereby offering a theoretical foundation for optimizing hydraulic fracturing and coal seam water infusion strategies.

In order to solve the problem of trackless transportation of personnel, materials and equipment in vertical shaft coal mines, in view of the restricted space of vertical shaft cages and the diversified transportation needs of underground, as well as the special working conditions such as poor ventilation and high slope underground, a platform-based R&D model is proposed to first develop a clean power and transmission platform based on which the development of a series of trackless rubber wheeled vehicle. The key technologies such as the overall design of the vehicle , determination of the main parameters, development of the platform, multi-mode design of the driving unit, expansion design of the work unit and cleaner emissions, safety assurance of the vehicle are described.The articulated trackless rubber wheeled vehicles for vertical shafts applying the above key technologies and design solutions have been verified in Wangcun coal mine of Jinneng Group and Shanxi Sanyuan coal industry.The test results show that: the technical performance of vehicle fully meets the needs of the production site, and the products covers the full range of functions and highly versatile. The research on the above key technology, design ideas and methods can solve the problems of the trackless vehicles enter and exit the vertical shaft cage directly, diverse transportation needs and tailpipe pollution, poor safety protection, which can accelerate the application of trackless transportation in vertical shaft coal mines.

Air-water heat exchangers are widely used in mine heat extraction owing to their advantages like simple structure and convenient installation and maintenance. Nevertheless, they are significantly influenced by air temperature; in low-temperature environments, they may even cause freezing at mine inlets, which in turn leads to the cracking of heat exchangers. Anti-freezing gravity heat pipes, a type of heat pipe technology capable of operating efficiently even in low-temperature conditions, offer an effective solution for mine heating in cold regions. This study investigates the heat transfer performance of gravity heat pipes under different charge amounts by analyzing experimental data of anti-freezing gravity heat pipes. By measuring data such as inlet and return water temperatures, mass flow rate, inlet and outlet air temperatures, and wind speed, the variation laws of key parameters like heat transfer rate, heat transfer coefficient, and thermal resistance under different charge amounts were calculated. The experimental results indicate that within the typical mine temperature range of 20 - 60 ℃, the heat transfer rate of the heat pipe increases monotonically with the rise in temperature. The optimal charge amount of the heat pipe corresponds to 43%-57% of the evaporator section volume (90-120 g), and the heat transfer rate is 121.21%-131.45% higher than that with the low charge amount of 30g. In this range, the heat transfer coefficient is 58.09-61.78 W/(m2·℃), and the thermal resistance is as low as 0.0806 - 0.0843 ℃/W. This research provides a basis for key parameters for the engineering application of gravity heat pipes in the field of mine heat extraction, and is expected to improve the efficiency and stability of mine heat extraction.

To address the poor flotation recovery of high–ash fine low–rank coal, this study proposes and validates a hydrophobic agglomeration–flotation process induced by an ester–type collector. Coal slime from the Dongsheng mining area, Inner Mongolia, was used as the research object to comparatively investigate the surface modification and agglomeration behaviors of n–dodecane and methyl laurate, as well as the effect of preconditioning agitation speed on agglomeration–flotation performance. In combination with contact angle measurements, Fourier transform infrared spectroscopy (FTIR), and X–ray photoelectron spectroscopy (XPS), the selective adsorption mechanism of the ester–type collector on the coal surface was elucidated. The results show that the contact angle of the raw coal was only 28.1°; after treatment with n–dodecane, it increased to 41.9° and further to 48.7° following hydrophobic agglomeration, whereas treatment with methyl laurate increased the contact angle to 50.7°, which was further enhanced to 56.6° after hydrophobic agglomeration. In terms of flotation performance, within a dosage range of 1000–4000 g/t, the clean coal yield increased from 19.87% to 27.12% with n–dodecane, while it increased from 41.11% to 58.78% with methyl laurate. When hydrophobic agglomeration was induced by preconditioning with methyl laurate, a stirring speed of 2000 r/min resulted in a clean coal yield of 64.02% with an ash content of approximately 20%. Moreover, the use of a composite reagent system with a methyl laurate to n–dodecane mass ratio of 1:3 achieved a clean coal yield of 61.73%, thereby balancing flotation performance and reagent cost. FTIR analysis revealed a significant reduction in the relative proportion of self–associated hydroxyl groups after methyl laurate treatment, while XPS analysis showed that the proportion of C–O species in the C 1s spectrum decreased to 15.01%, accompanied by a pronounced decrease in C–O species in the O 1s spectrum, indicating that ester–type collectors preferentially interact with oxygen–containing sites such as hydroxyl groups via weak hydrogen bonding and/or dipole–dipole interactions.

To address the low utilization rate of mine exhaust heat and the shortcomings of traditional heat exchange technologies, this paper proposes a heat pump heating system based on an ethylene glycol interwall heat exchanger for recovering mine exhaust heat and preventing freezing at the wellhead. Through theoretical analysis, mathematical model construction, and AMESim simulation, the influence of the inlet parameters of the ethylene glycol solution on the heat exchange performance was studied, and the operating conditions of the system were optimized. The results show that when the inlet temperature of the ethylene glycol solution increases from -6 °C to 3 °C, the heat exchange capacity of the heat exchanger decreases from 185 kW to 110 kW; when the inlet velocity of the ethylene glycol solution increases from 1.5 m/s to 3 m/s, the heat exchange efficiency of the heat exchanger increases from 61.5% to 81.94%. When the inlet temperature of the ethylene glycol solution increases from -6 °C to 3 °C, the coefficient of performance (COP) of the heat pump system increases from 2.82 to 3.69, and the heating capacity of the heat pump system increases from 147.85 kW to 151.52 kW. This study provides a feasible technical solution for the efficient recovery of low-grade waste heat in mines and has significant application value for achieving energy conservation and emission reduction in the coal mining process.

Under the strategic backdrop of the “dual carbon” goals, the low-carbon transformation of the coal mining industry is now urgent. Addressing the issues of energy waste and low coal production efficiency caused by the operation of coal cutters in fully mechanized mining faces, this paper proposes a method for the synergistic optimization of energy efficiency and operational effectiveness of coal cutters based on cutting resistance prediction, aiming to achieve efficient and energy-saving operation of coal cutters. First, to address the complex and variable operating conditions in fully mechanized mining faces, an optimized radial basis function neural network (SPSO-RBF) is employed to accurately predict the cutting resistance of coal cutters; second, by analyzing the resistance encountered by coal cutters during operation, an energy consumption model based on cut-ting resistance is established; furthermore, the non-dominated sorting genetic algorithm-II (NSGA-II+ARSBX) based on adaptive rotary simulated binary crossover is used to establish a multi-objective optimization model with the objectives of minimizing energy consumption, maximizing coal production efficiency, and maximizing block coal area, and the optimized traction speed and drum speed of the coal miner are obtained; finally, engineering case verification is conducted based on coal miner data from the Jinjie Coal Mine. The results show that under the one-cut process, energy consumption is reduced by 20.04%, coal mining productivity is increased by 45.71%, and the area of lump coal is increased by 41.56%, verifying the correctness and effectiveness of the proposed model and algorithm.