To address the issue that existing natural radiation-based coal and gangue identification methods cannot directly calculate the gangue mixing rate at discharge outlets, a monitoring system for coal discharge quantity in fully mechanized top coal caving based on a binocular camera has been designed. This system aims to calculate the dilution ratio by monitoring the discharge volume at the coal discharge port and combining it with the quality data of gangue provided by the natural radiation identification method, thus assisting in determining the appropriate timing for closing the discharge port. The system employs a grating projection method to project a grid image of the coal flow surface transported by the scraper conveyor near the discharge port. It utilizes a binocular camera to scan the grating and obtain high-precision point cloud data of the coal flow profile. Through projection and micro-mesh partitioning, an organized three-dimensional point cloud model of the coal flow is constructed. A finite element volume calculation method is introduced for slicing the model, and the trapezoidal rule is used to calculate the volume of each slice, leading to the overall volume of the coal flow through summation. Additionally, a telescopic support structure has been designed to adapt to different field requirements, allowing for flexible adjustment and safety protection of the detector. Laboratory experiments for coal quantity monitoring demonstrate that the system maintains a measurement error of less than 5% under various coal flow accumulation conditions, indicating high accuracy and good stability. Specifically, under flat and piled conditions, the measurement errors are controlled within 5% and between 4.6% and 4.9%, respectively, with a root mean square error of 0.2952. The coal discharge quantity monitoring system designed in this study is effective and can provide reliable real-time monitoring data for the intelligent coal discharge in fully mechanized mining faces, thereby supporting the determination of the dilution ratio. This has significant implications for improving the accuracy and practicality of automatic coal gangue identification technology. The successful implementation of this system provides a new technical means for the intelligent construction of coal mines and has broad application prospects.

As the core equipment for the development and utilization of deep resources, the hoisting system during the construction of ultra-deep shafts faces complex dynamic loads and extreme working condition challenges. The dynamic load-bearing safety of hoisting wire ropes directly restricts the safe construction and operational efficiency of ultra-deep shafts. In response to the issues that the calculation of the minimum safety factor for the load-bearing capacity of hoisting systems in China's ultra-deep shaft construction does not fully consider time-varying loads and the differences with international minimum safety factor standards, this paper takes the Sanshandao Gold Mine as the research object. It compares and analyzes the differences in the ultimate hoisting height and hoisting load under the theoretical calculations of the minimum load-bearing safety factor for wire ropes in domestic and international contexts. Furthermore, a multi-body coupled dynamics model of the hoist-wire rope-hoisting container is established, and a dynamic safety factor calculation method based on time-varying load spectra is proposed. This method reveals the vibration characteristics, dynamic tension evolution, and dynamic safety factor variation patterns of the hoisting system during the acceleration, constant speed, and deceleration phases. Additionally, the influence mechanisms of key factors such as sudden changes in hoisting speed, elastic vibration of the wire rope, and load fluctuations on system safety are analyzed. The research results indicate that during the hoisting process, as the hoisting height increases, the amplitude and frequency of longitudinal and torsional vibrations of the wire rope and bucket gradually increase, while the lateral vibration shows a trend of initially increasing, then decreasing, and finally stabilizing. Based on the domestic and international theoretical calculations of the wire rope load-bearing safety factor, the dynamic safety factor of the wire rope increases with the hoisting height during the hoisting phase, while it decreases with the lowering height during the lowering phase, with the maximum dynamic fluctuation amplitude occurring during the acceleration phase.

Aiming to reasonably demonstrate the downward mining feasibility of the bottom coal seam under the repeated mining in close multiple coal seams, a study of the failure characteristics and downward mining feasibility was conducted based on Qianjiaying coal mine of close multiple coal mine with downward mining using theoretical analysis, numerical simulation, and on-site detection. Based on the theory of slip line field in coal seam mining floor, the failure depths of the floor were 7.85 m and 4.18 m after the initial and repeated mining of upper coal seams, by optimizing the stress zone of the abutment pressure in front of the coal wall. The bottom coal seam was not affected and maintained good continuity and integrity. The numerical simulation results showed that the fracture number in the floor increased under the influence of the initial and repeated mining of upper coal seams, but the development of fracture depth remained basically unchanged. The fractures were densely developed to the main roof of the bottom coal seam. The GPR on-site detection results showed that the electromagnetic signal distribution of the floor was relatively uniform after the initial and repeated mining of upper coal seams, and there were no abnormal phenomena such as large-scale fluctuations of electromagnetic signals. The roof of the No.9 coal seam can be maintained integrity with good mining feasibility.

In view of the problems of difficult control of surrounding rock stability and frequent disasters during the mining of thick and hard overburden roof working face passing through faults. This paper adopts theoretical analysis, numerical simulation, and field test to study the characteristics of overlying rock migration and the dynamic evolution law of surrounding rock stress during the working face passing through faults. A collaborative prevention and control technology of "fracture-injection-discharge-support" is proposed for the working face passing through faults. Research has shown that as the size of coal between the working face and the fault plane decreases, the risk of instability caused by the sliding of thick and hard roof along the fault plane increases. There is a stress barrier effect on the fault plane, with an increased stress zone in the hanging wall area and a decreased stress zone in the footwall wall area. The working face passing through a fault is divided into five periods, fault stationary period, fault activation period, fault movement period, fault stress release period, and fault stability period. Before the fault movement period, the coordinated measures of rock unloading and solidification are adopted in stages, which can improve the stress distribution environment of the surrounding rock and the structure of the surrounding rock in the mining site, effectively reduce the mining pressure and impact dynamic manifestation of the working face, improve the stability of the surrounding rock in the fault area, and achieve safe and smooth passage of the thick and hard overlying rock roof working face through the fault.

To protect the safety of personnel in buildings adjacent to gas extraction pump rooms, it is necessary to set up blast walls to separate areas with explosion hazards in the factory building. Due to the lack of relevant regulations in the coal industry, there is currently no content related to blast resistant design. This article refers to relevant anti explosion design specifications in the petrochemical industry, anti explosion chamber design specifications, and other literature and books to introduce the characteristics, modes of action, and calculation of explosion shock wave related parameters of indoor and outdoor explosion loads. It briefly explains the process and formula application methods of anti explosion structural design. On this basis, combined with the layout of the Wangfeng Mine Gas Extraction Station, an anti explosion wall design was carried out adjacent to the gas extraction pump room building, providing safety protection for its internal staff.

Aiming at the problem that the bottom of deep drilling shaft wall is easy to produce cracks in the process of pouring, curing and sinking, taking the north air shaft of Taohutu Coal Mine as the engineering background, the stress analysis of the bottom of deep drilling shaft wall and the development and application of high performance fiber concrete are carried out. The stress analysis of the bottom of the semi-elliptical rotating flat spherical shell shaft wall is carried out by numerical simulation method, and the key tensile stress area is identified. The results show that there is a significant tensile stress area outside the top of the bottom of the shaft wall, and the maximum principal stress reaches 0.56 MPa, indicating that there is a risk of tensile cracking in the concrete. Through material optimization and orthogonal test, the optimal mix ratio of fiber concrete C75 at the bottom of the shaft wall is cement : fly ash : ground slag : stone : sand : water : water reducing agent : fiber = 400 : 75 : 85 : 1011.8 : 732.6 : 145.6 : 13.44 : 2.0. The crack resistance of fiber reinforced concrete and ordinary concrete was compared by plate crack test. The results showed that the crack resistance of fiber reinforced concrete was significantly better than that of ordinary concrete. The application of the mix ratio in the engineering site shows that no cracks appear at the bottom of the pouring shaft wall, thus ensuring the construction quality of the bottom of the shaft wall. The research results of this paper can effectively solve the problem of construction cracks at the bottom of the wellbore in deep drilling, and effectively improve the anti-cracking and anti-permeability of the bottom structure of the wellbore and the construction safety.

To improve the construction efficiency and safety of shaft boring machines (SBMs) under freezing conditions in soft and water-rich complex strata, this study investigates key technologies for excavation and support construction based on the mechanical characteristics of frozen rock masses, focusing on optimizing cutting parameters and support processes to establish a systematic technical scheme for frozen shaft construction. Full-scale experiments and parameter optimization analyses were conducted to explore the effects of cutting depth, drum rotation speed, and traction speed on rock-breaking efficiency and construction stability, and a high-efficiency shaft wall support model was proposed. The results show that the optimized low rotation speed and shallow cutting depth cutting process reduces cutting specific energy consumption, improves excavation efficiency, and effectively minimizes frozen wall disturbance, thereby enhancing construction stability. Meanwhile, the adoption of a double-layer reinforced concrete shaft wall structure, combined with an external synchronous support method and an internal segmented slip-forming process, significantly improves shaft wall support quality. Additionally, the "excavation–support–muck removal" synchronous construction mode enhances overall construction efficiency. The research findings provide technical support for shaft construction in soft and water-rich complex strata under freezing conditions and serve as a reference for optimizing similar engineering projects.

Abstract：Ground directional overrun area management grouting reinforcement has become an effective means to liberate the graystone aquifer in the upper section of Taiyuan Group in the management process of the bottom plate bearing pressure water damage in North China Coalfield, how to objectively analyze and evaluate the construction data in the process of grouting, reduce the workload of construction verification downhole and at the same time ensure that the work face is safe and efficient back to the mine has become an urgent problem to be solved at present. According to the comprehensive analysis of the geological condition and construction elements of 21106 working face, multi-layer tuff bearing pressure water on the L10 tuff aquifer was selected to carry out the management mode of locking the edges first and then grouting, and based on the actual construction data in the grouting site, a comparative analysis was carried out on the grouting pattern, leakage pattern, and water outflow pattern of the grouting transformation drill holes. Engineering practice shows that: the structure, drilling construction sequence, construction time interval is the main factors affecting the ground drilling grouting volume; the location of slurry leakage is related to the grouting pressure, and the structure, grouting pressure and construction sequence are the main factors affecting the size of the leakage volume; downhole inspection is carried out after the end of the ground grouting, and the gushing volume of the test borehole outflow point is less than 10m3/h, and the final borehole water pressure is lowered from 2.23Mpa to 1.5Mpa, the distribution of water pressure is in the form of an island, and there is no abnormal area in the physical exploration test, which indicates that the effect of bottom plate grouting transformation is safe and reliable. The research results are successfully applied to realize the safe mining of working face on multi-layer tuff bearing pressure water under complex geological structure, and provide guidance and support for the overrun management of water damage on the bottom plate of the same type of mine.

Focusing on the dynamic pressure manifestation and roof disaster mechanisms under continuous min-ing of large mining height working faces, the typical case of roof caving in the 2-2 coal seam at the Xiaobaodang Coal Mine was used as the background. The support resistance and the strong dynamic pressure before and after abnormal pressure were analyzed. On this basis, through a comprehensive ap-proach that includes deposition analysis, numerical simulation, microseismic monitoring, model testing, and field investigation, the mechanism was revealed. The results show that the dynamic pressure mani-festation is more pronounced on the tail side, with continuous pressure appearing before the manifesta-tion of dynamic pressure, possibly accompanied by a relatively calm period. When the working face comes under pressure, the intensity is high, and the affected area is large. The rock layer structure indi-cates lateral alternation and rapid changes in lithology and rock layer thickness, with multiple thick hard rock layers and thin unstable roof layers developing simultaneously in the vertical direction. The damage zone spans multiple working faces, showing synchronous damage and fracture characteristics at different roof levels. Strong dynamic pressure is concentrated at the tail, with damage and stress growth more pronounced on the unsupported side, displaying unevenness and differences. The thick hard roof structure in the goaf can be reactivated and fractured, leading to microseismic events, roof dynamic loads, and subsidence of high-level rock layers. The research findings provide significant reference for disaster early warning, prevention, and safety production in continuous mining of large mining height working faces.

Abstract: In order to improve the effect of unloading gas extraction by hydraulic punching drilling in low-permeability coal seams and eliminate the negative effect of punching-induced concentrated stress on gas flow, a method of enhanced gas extraction by hydraulic punching and coordinated gas injection and driving is proposed. In order to explore the factors affecting the effect of hydrofluidic punching and synergistic gas injection, a coupled flow-solid model of multi-component gas storage and transportation process was established, and the effects of different punching hole equivalent diameters, gas injection pressures, and drilling spacings on the effect of increasing gas flow and eliminating surges were analysed. The results show that increasing the equivalent diameter of punched holes can significantly increase the pressure unloading range of the coal seam, improve the effect of gas flow enhancement and shorten the period of blasting abatement. Increasing the gas injection pressure can improve the effect of gas flow enhancement, reduce the flow decay per unit time and shorten the period of blasting. Drill hole spacing does not significantly affect the effect of gas flow enhancement and blasting elimination, but the lagging phenomenon of production increase may occur when the drill hole spacing is larger. The equivalent diameter of the punched holes has a significant effect on the gas flow and content at the initial stage of gas injection; the larger the equivalent diameter is, the larger the initial gas flow is and the smaller the initial gas content is. Field engineering test results show that after adopting the synergistic gas extraction technology of hydraulic punching and gas injection in low-permeability coal seams, the maximum gas extraction flow rate of the drilled holes is increased to 0.0325 m3/min, and the flow rate is increased by 44%~85%, which has a good application effect.

Abstract: In order to determine the optimal layout parameters of the high level borehole in the goaf of 2109 working face of Jining Coal Mine, the complete overlying rock movement process under the goaf of 2109 working face is analyzed, and the gas distribution law under the Y-type ventilation in the goaf is studied. The results show that: (1) The fracture zone has asymmetric development characteristics under the condition of goaf retaining, the maximum height of the caving zone and fracture zone on the cut side is 22 m and 82 m, and the maximum height of the caving zone and fracture zone on the uncut side is 20 m and 86 m. (2) Gas is mainly distributed in the depth of the goaf under Y-type ventilation, and the rich area is located in the fracture zone on the side of the uncut top, and the maximum gas concentration is 42%. (3) The optimum height and spacing of the upper borehole are further determined to be 70 m and 20 m, respectively. Under this parameter, the maximum gas concentration near the mining face decreases from 1.94% to 0.497% after 160 days of pumping. (4) According to the site conditions of the working face 2109, eight high level boreholes were designed to extract gas from the gob. In the early stage of extraction, the daily extraction volume of boreholes 1 to 8 showed a gradual increase, which was in line with the distribution of gas before extraction. After extraction, the extraction volume of holes 4 to 8 on the uncut top side was greater than that of holes 1 to 3 on the cut top side. The law of gas enrichment under the condition of cutting roof and retaining roadway is confirmed, which can provide reference for gas extraction in the gob under Y ventilation.

The microseismic monitoring technology is a method to evaluate the dynamic disaster risk through the statistical analysis of the microseismic data and the actual production by monitoring seismism caused by coal mining. Microseismic monitoring technology has made great progress in the aspects of the optimization of network layout, source location algorithm and monitoring of rock burst, etc. In recent years, many innovative results have been achieved in the fields of roof rupture monitoring and water damage monitoring. However, there are still many problems that limit the further development of microseismic monitoring technology in coal mines, such as insufficient depth analysis of microseismic data, single wave velocity structure affecting location accuracy, low location accuracy of Z-value of near-horizontal coal seam, and inconsistent energy algorithms. The future development of microseismic monitoring technology is mainly focused on the innovation and upgrading of the system hardware and software and algorithm, data deep analysis, intelligent operation and other directions, so as to achieve the purpose of real and reliable data, high source location accuracy, intelligent and friendly operation and effective guidance to safety production.

A comprehensive understanding of the spatio-temporal characteristics and causal factors associated with major and above coal mine accidents is of significant practical importance in the prevention of such incidents. This paper employs a concentration index and spatial analysis method to examine major and above coal mine accidents in China between 2013 and 2023. The findings indicate that: (1) The number of accidents decreased significantly from 2013 to 2019, and the number of accidents stabilized from 2020 onwards. However, the number of fatalities and direct economic losses increased year by year. There has been a notable improvement in the incidence of gas accidents, while the number of roof accidents has increased. In contrast, water accidents have remained relatively stable, although they have resulted in significant economic losses and have had a considerable impact on local state-owned coal mines. (2) The month of the accident is divided into four phases, each characterized by a distinct level of discretization. The period from October to December was found to have the highest concentration of accidents. The distribution of accidents exhibited a spatial correlation, forming three clusters of high values in a northeast-central-southwest direction. The center of gravity path demonstrated a pattern of alternating northeast-southwest movements. (3) The primary cause of accidents in recent years has been the illegal organization of production. While the issue of illegal operations has been addressed, the problem of inadequate support persists, and the underlying causes of different types of accidents vary. The indirect reasons from 2013 to 2017 were mainly due to inadequate enterprise management capabilities and technical management, whereas in the period between 2018 and 2023, they were predominantly slack corporate management and inadequate employee professionalism. (4) Late reporting and concealment are prevalent in coal-producing provinces, and the involvement of public officials is on the rise. Late reporting and concealment are more likely to occur when the primary cause of accidents originates from the management of enterprises.

The long-term accumulation of coal gangue will form acidic coal gangue leachate containing heavy metals such as lead and chromium under the erosion of weathering rainwater, seriously polluting the soil and groundwater environment of the mining area. This study used bentonite, fly ash, and fly ash as raw materials, and added sodium polyacrylate to prepare bentonite fly ash fly ash sodium polyacrylate composite anti-seepage material (BFS), and investigated its anti-seepage performance.The research results found that a four factor interaction experiment was conducted by adding fly ash and sodium polyacrylate to the mixture of bentonite and fly ash. The optimal mass ratio of bentonite, fly ash, fly ash, and sodium polyacrylate obtained based on the response surface Central Composite test method was 65:35:37.5:4. At this ratio, the permeability coefficient of BFS was 1.35 × 10-8 cm/s, the cation exchange rate was 54.09 cmol+/g, and the free expansion coefficient was 8.55 mL/2g, meeting the requirements of anti-seepage performance.The development of BFS fully utilizes the advantages of fly ash and sodium polyacrylate, which has practical significance in reducing the cost of reclamation in coal mining subsidence areas, increasing the comprehensive utilization path and utilization rate of fly ash and bentonite. At the same time, it provides theoretical support for the design, application, and effectiveness evaluation of the anti-seepage layer for coal gangue landfill sites.

Coal mine safety management deficiencies are the primary cause of coal mine accidents. However, the current situation regarding the investigation and rectification of these defects are not optimistic. There is still a gap between coal mine safety management and modern management standards. In order to reduce the defects in coal mine safety management in China and promote the implementation of investigation and rectification work, this paper explores the development history of coal mine safety management issues, analyzes the current research and application status of these issues, proposes an accident causation model primarily focused on management deficiencies, and discusses the concept, specific content, and future prospects of coal mine safety management shortcomings. The study shows that the sensitivity, specificity, complexity, hiddenness, and ambiguity of coal mine safety management defects is the fundamental reasons that make it difficult to implement in China's coal mine practice. Finally, development suggestions regarding the theoretical model and practical process of investigating and rectifying defects in coal mine safety management are provided based on the research results.

In order to promote the progress and quality improvement of the remanufacturing technology of coal mine anchor excavator, the current status of the remanufacturing of anchor excavator and the drafting of technical specifications and standards were analyzed; Studied the repair of cracks in structural components, repair of wear-resistant plates, repair of cutting drums, remanufacturing of sliding frames, remanufacturing of reducers, remanufacturing of electric control box boxes, and other key technological iterations; Elaborate on the remanufacturing process flow, testing and testing of key components and systems, and quality control system. We have completed the remanufacturing of 14 anchor excavators, including 12 imported anchor excavators and 2 domestically produced anchor excavators, with good performance. Aiming at the problems of weak theoretical foundation, imprecise process, and lack of advanced technology in remanufacturing, innovative ideas are proposed, namely: treating remanufacturing of excavator anchor integrated machine as a new product development, strengthening the application of remanufacturability evaluation and service life prediction methods, strengthening remanufacturing design, applying remanufacturing experience to excavator anchor integrated machine design, highlighting the value of information construction and expanding digital applications, and innovating remanufacturing service concepts.

In order to address the challenges in flexible formwork gob-side entry retention construction—such as prolonged processes, high labor intensity, excessive personnel requirements, and low efficiency during concrete pumping equipment relocation, pipeline layout, and other procedures—an independently developed?self-propelled concrete pumping system for flexible formwork gob-side entry retention?has been introduced. To investigate the vibration characteristics of the conveying pipeline in the self-propelled concrete pumping system, a pipeline model of the pumping system was firstly developed. The forces on straight and elbow pipes during pumping were analyzed to determine boundary conditions and parameters for the pipeline model.. Secondly, through free modal analysis and modal linear superposition of a single-section pump pipe, the modal zero position of the pipe section was identified and designated as the pipeline support point. The relationship between the number of pipeline sections and the free modal frequencies was summarized. Subsequently, a harmonic response vibration analysis was perfomed on the conveying pipeline under combined loads of concrete gravity, friction, and pipeline self-weight. The vibration amplitudes and stresses of the pipeline under different support constraints were obtained. Finally, a rigid-flexible coupling analysis of the pipeline was conducted to derive support reaction forces and validate the harmonic response results. The results indicate that the modal zero position (optimal support location) is located?415 mm from the pipe end; the first six free modal frequencies of a single-section pump pipe exhibit an inverse hyperbolic relationship with the number of pipeline sections; the optimal support spacing for the pipeline is 1 section; and gravity of the mobile support device must exceed 117.74N to ensure stability.