The stability of the foundation of photovoltaic power station construction in coal mining subsidence area will directly determine the feasibility of its construction and long-term operation. This paper studies the construction of photovoltaic power station in a coal-mining subsidence area in southwest Shandong Province, divides it into three types of buildings (structures) according to the sensitivity of surface deformation, summarizes the main sources of foundation settlement deformation, determines the depth of influence of the load of photovoltaic power station construction in coal-mining subsidence area, and calculates the cumulative settlement deformation of photovoltaic power station by combining soil mechanics analysis and probability integral method. Based on the existing standard and the nonlinear fuzzy comprehensive evaluation method, the foundation stability analysis is carried out respectively. Finally, the applicable conditions of the two foundation stability analysis methods for the construction of photovoltaic power stations in coal mining subsidence areas are pointed out. The results show that: (1) the selection of the criterion for the depth of load influence should be based on the deformation resistance of the facility structure and the occurrence conditions of the goaf, and the high criterion should be used for the high-rise structures and complex goaf foundations. (2) The settlement amount of photovoltaic power station construction calculated based on soil mechanics analysis method and probability integral method is 164mm and 1456mm, respectively. By comparison, it can be seen that the foundation settlement of the project is mainly the surface residual deformation of the goaf. (3) At present, the evaluation methods of foundation stability can be divided into the current standard evaluation and nonlinear fuzzy comprehensive evaluation. Both methods are suitable for planar objects, but the nonlinear fuzzy comprehensive evaluation method is more suitable for point objects such as high-voltage transmission lines. (4) The result of nonlinear fuzzy comprehensive evaluation of foundation stability in this engineering example is more consistent with the field practice, which proves the feasibility and effectiveness of nonlinear fuzzy comprehensive evaluation in the application of "photovoltaic + coal mining subsidence area" model of foundation stability evaluation.

This paper briefly introduces the basic situation of Tarahao Mine,with a focus on optimizing the design from eight aspects: industrial site selection, terrain utilization, development methods, shaft support, auxiliary transportation, roadway layout, permanent magnet motor application, and working face production. Three innovative points have been extracted, including one drilling hole for cutting into multi-layer tunnels, the application of an integrated excavation anchor machine for soft rock, and support along the channel. Summarize the ways and determining parameters for improving the production capacity of three soft strata mines. It also provides valuable experience for the construction and optimization design of similar mines in the future.

Aiming at the problems of coal mining under constructions, difficulty in handling ground gangue of YiQiao Coal Mine, through theoretical analysis, scheme comparison, equipment selection and other methods, the scheme of non-lifting after intelligent separation of underground gangue is proposed, the underground gangue filling mining technology is studied, and the appropriate separating and filling equipment is selected. The cement, fly ash, water and gangue which proportioning 1:1:2.57:20 is confirmed as the dense cementitious filling material, the strength of the filling body is greater than 2.98MPa, the production capacity of the filling working face is 13000t/a, a whole set theories of underground gangue non-lifting through separating and filling system is formed, the engineering application shows that the system satisfies the requirements of coal mining under construction, liberates the amount of coal resources under construction, ensures the effective capacity of the shaft lifting system, digests the mine gangue, and realizes the requirements of green mining in YiQiao Coal Mines.

To improve the main well net lifting capacity, TDS intelligent coal separation system has been more and more widely applied to the underground instances. This article discusses the operating rules of the system, analyzes its corridor and cavern group layout form and cross-section, and elaborates on its plane layout and vertical layout. It summarizes two main layout methods that have a significant impact on the height of TDS intelligent coal separation main cavern rooms, based on their different layout methods, and explores the selection of supporting measures for TDS intelligent coal separation main cavern rooms in large cross-section. On this basis, based on the actual production system of the Three Rivers Mining Mine, the underground TDS intelligent coal separation system corridor and cavern group layout design example is presented, providing a reference for similar mine transformation and design projects.

In response to the existing coal resource occurrence, development and mining status, and the demand for later coal mining in Xiezhuang Coal Mine, according to the industry policy of restricting mining beyond one kilometer in Shandong Province, proposed a technical transformation plan of "mixed vertical shaft, underground inclined shaft, and horizontal main roadway" for areas within a kilometer of the mine. Researched and determined the pithead location and equipment plan of the newly built shaft, reasonable adjusted mining areas division and development layout. Optimized the layout of mining roadway and working face, proposed filling and mining technology for the area under construction. Optimized and transformed the main production systems such as transportation, ventilation, drainage, and power supply. After the renovation project is completed, it could effectively solve the problems of mines, multiple production links, complex systems, and high safety hazards, extend the service life of the mine and achieve safe and efficient production in the mine.

For coal mines with thin bedrock and thick loose layers as the background, the occurrence of water and sand inrush disasters generally presents the characteristics of sudden and frequent occurrence. Such accidents are catastrophic and destructive. Production poses a great threat. Therefore, the key to preventing the occurrence of water and sand inrush disasters is to carry out advanced prediction, early warning and prevention work for such disasters. The multi-source information zoning evaluation method and the advanced production layout optimization technology provide a basis for the prevention and control of mine water and sand inrush disasters.

The underground reservoir technology system is a technical method to improve the utilization rate of water resources in the western region and alleviate the water shortage in mining areas. A reasonable coal pillar width of the underground reservoir is an important guarantee for the normal operation of the underground reservoir. Taking the underground reservoir of Daliuta Coal Mine as the engineering background, this paper theoretically calculates the reasonable reserved width of the coal pillar dam body of the reservoir, puts for-ward the main influencing factors of the stability of the coal pillar dam body from the perspective of the combined action of mining stress and initial crustal stress, and analyzes the influence of different influ-encing factors on the stability of the coal pillar dam body. The research results indicate that: (1) the rea-sonable width of the coal pillar dam body in the underground reservoir of Daliuta Mine is 27.01 m; (2) The higher the mining height of the working face, the smaller the width of the coal pillar, the higher the level of deviatoric stress inside the coal pillar, and the lower the stability of the coal pillar; (3) The smaller the lateral pressure coefficient of the initial crustal stress field, the larger the range of crustal stress angle deviation from 0 °, the higher the deviant stress level in the coal pillar, and the lower the stability of the coal pillar.

The coal-fired boilers in the original heating system of Huacaotan Coal mine are now aging and lacking in output, and do not meet the requirements of current environmental protection policies. In order to transform the original heating system after the elimination of boilers, ensure the heating and heating effect, and guarantee the safe production, energy conservation and environmental protection of coal mines, the existing available high-quality waste heat resources and heat load status of coal mines are investigated and analyzed. According to the research results, a scheme of "coal mine waste heat resource heating system" is proposed and established, and the investment and operation costs of this scheme and the electric hot water boiler heating scheme are compared and analyzed. The research results show that the total investment and operation cost of the coal mine waste heat resource heating system is expected to be the same as that of the electric hot water boiler heating system in the 3.3th year. Since then, the annual operating cost has been saved by 67.58% . This research utilizes high-quality waste heat resources from coal mines for heating reduces investment and operating costs, reduces pollutant emissions, and generates significant economic and environmental benefits. It has a positive significance for the construction of low-carbon coal mines.

Aiming at the problems of difficult mechanical construction and low construction efficiency of 1902 S return airway with large dip angle inverted trapezoidal roadway in Great Wall No.5 Mine, after field investigation and equipment investigation, the purpose of intelligent construction of coal mine is carried out, and the related equipment of excavation and support is further optimized and improved. The automatic and rapid excavation process of“high-power comprehensive road-header + monorail crane four-arm hydraulic bolt drill + self-moving tail + small diesel monorail crane + belt centralized control”is formed. The results show that the use of intelligent equipment and automation technology greatly reduces the number of on-site construction personnel. At the same time, the process effectively utilizes the upper space of the roadway, and realizes the cooperative operation goal of “walking up and down, driving and supporting connection” between the road-header and the monorail crane. Compared with the original manual air drilling process, the new process can carry out the footage construction of double row spacing and three row spacing according to the roof condition. The daily footage increased from 7.8m (double row spacing-three shifts) to 15.6m (three row spacing-four shifts), the monthly average footage of double row spacing reached 368 m, and the monthly average footage of three row spacing reached 392m. The maximum increase was 42.03%. It provides an important reference for solving the problem of rapid excavation of roadways with special section shapes such as inverted trapezoid (inclined roof).

In view of the technical problem that asymmetric large deformation of mining roadway under the influence of fault and mining disturbance, this paper takes the return air channel of Qipanjing I030902 as the research background, uses the methods of theoretical analysis, numerical simulation and field test to study the stress characteristics, displacement and plastic zone expansion law of roadway surrounding rock under different fault pillar widths, and analyzes the mechanism of asymmetric large deformation of surrounding rock of mining roadway near fault, The results show that the main causes of asymmetric deformation of roadway are abnormal stress in fault fracture zone, low rock mass strength and poor uniform bearing effect of support system. Combined with the deformation characteristics of surrounding rock and numerical simulation inversion results, a combined support technology of "full anchor cable+grouting reinforcement" is proposed. The monitoring results show that within 60 days after the repair, the maximum convergence of the two sides of the return air passage is 182 mm, and the maximum displacement of the top and floor is 176 mm. During the mining process of the working face, the maximum deformation of the two sides of station 1 # is 463mm, and the maximum displacement of the top and bottom plates is 485mm. This scheme can effectively improve the stress environment of the surrounding rock of the roadway in the fault area, reduce the development of the surrounding rock plastic zone, and ensure the normal use of the mining roadway.

In order to solve the problems of difficult and passive construction and complex process during roadway excavation under complex geological conditions, based on the engineering background of the machine lane in 818 in Xinhu Coal Mine of Huaibei Mining Industry, this paper puts forward the scheme of using ground directional drilling pre-grouting technology to control the surrounding rock of roadway before excavation. FLAC3D software is used to simulate the deformation characteristics of surrounding rock before and after grouting. After the field grouting test, the diffusion of slurry in surrounding rock is observed by means of borehole peeping. Combined with the geological conditions and construction characteristics of the roadway, the support form of gangue roof roadway is determined, and the long-term continuous mine pressure monitoring is carried out in grouting area and non-grouting area. The results show that under the same support form, compared with the non-control area, the two-side convergence and roof subsidence in the control area are reduced by 31.82 % and 36.77 % respectively, which proves that the ground directional drilling pre-grouting surrounding rock modification technology has a good effect on strengthening the self-bearing performance of surrounding rock and improving the stability of roadway.

The full-face hard rock tunnel boring machine ( TBM ) needs to adjust the pose of the cutterhead and the fuselage according to the position of the coal seam during the tunneling process of the coal mine gas extraction roadway, so that a certain safe distance can be maintained between the TBM and the coal seam. At present, the steering of the TBM in the tunnel rock roadway still needs to rely on the driver to artificially control the rotation angle. Due to the instability and non-real-time nature of manual operation, over-excavation and under-excavation of the tunnel rock roadway often lead to TBM jamming. Therefore, it is an inevitable trend of TBM intelligence in the future to adopt a real-time, stable and reliable control method to replace or assist the manual control of TBM pose. In this paper, a TBM pose control method is proposed for the turning and pose control of small diameter ( diameter less than 6m ) TBM in coal mine gas extraction roadway. The co-simulation model of TBM propulsion system is built by AMESim simulation platform and ADAMS dynamics software. Combined with the design axis of parametric characterization of extraction roadway, the master-slave control method is used for the propulsion system, and the PID controller is designed for the overturning angle and yaw angle of cutterhead to realize the real-time control of cutterhead pose. The effectiveness of the pose control method is verified by simulation analysis, which can be well applied to the turning pose control problem of small diameter TBM in coal mine gas extraction roadway.

The coal bearing stratum of Yuanbaoshan open-pit coal mine is covered by the Quaternary gravel layer with strong water yield formed by the alluvial and proluvial deposits of Yingjin River. Since the mining of the mine pit, the drainage water is beening huge, he quaternary system water inflow accounts for 95% of the total drainage, resulting the environmental risk and economic burden have been increasing. In order to effectively protect the groundwater resources and reduce the drainage volume of the mine, adopted the curtain water cutoff curtain technology of vertical concealed laying of impermeable membrane and pouring and filling of impermeable concrete to treatment the quaternary groundwater. A falling bottom water interception curtain with a plane length of nearly 3600m, effective thickness of more than 0.8m, and wall depth of more than 40m was built on the +452 m flat plate at the southeast side of the mine pit. Verified by physical excavation, comparison of water levels on both sides of the curtain and change of water volume in the pit, the water cutoff curtain effect is remarkable, which completely solves the problem of quaternary groundwater infiltration in the southeast of the pit. The implementation of the water cut-off curtain in Yuanbaoshan open pit coal mine once again verified the feasibility of the curtain water cut-off technology in the seepage interception and emission reduction of open pit coal mines, which has important demonstration and promotion significance for open pit coal mines and other mines with similar problems.

In response to the problem of strong rock pressure during the full thickness mining of the irregular working face with high mining height near the fault zone, this paper takes the mining period of the 7447 irregular working face in a certain mine in Shandong as the research object. Through on-site investigation, theoretical analysis, numerical simulation, and rock pressure observation, the characteristics of overlying rock fracture and its induced mechanism during the mining period of the 7447 irregular working face were studied. The results show that during the mining period of the 7447 irregular working face, the roadway with a wide working face section is more prone to damage than the narrow working face section under static load, and the transportation roadway near the fault zone is more prone to deformation and damage compared to the track roadway; The height of overlying rock fracture during mining is mainly controlled by the width of the working face. When the width of the working face is larger and the filling degree of the goaf is poor, it is easy to form a trapezoidal structure with a larger damage height above the goaf; When the width of the working face is large, the high level rock layers that did not break when the width of the working face was small also begin to break. The height of the trapezoidal body increases, the thickness of the loading layer increases, and the compressive strength of the working face increases. The variation of on-site support working resistance with advancing distance further reveals the mechanism of mining induced erosion in irregular working faces, and corresponding prevention and control measures are proposed from the perspectives of weakening the combination of dynamic and static loads and strengthening the control of tunnel surrounding rock system.

Existing researches on the evaluation of pressure relief effects are mostly aimed at inclined or gently inclined coal seams. The applicability to near-vertical extra-thick coal seams is not yet known. It is difficult to judge the pressure-relief effect of near-vertical extra-thick coal seams after pressure-relief blasting. Taking the B3+6 coal seam in the southern mining area of Wudong Coal Mine as the engineering background, combined with on-site monitoring and theoretical analysis, the decompression effect of the near-upright extra-thick coal seam is studied by using the mine transient electromagnetic. The study found that the apparent resistivity of the coal seam and its roof and floor coal in the pressure relief area after the implementation of deep and shallow hole pressure relief blasting and coal seam water injection is significantly reduced compared with the unrelief area, and the apparent resistivity of the roof is reduced by 50%~58.33. %, the coal seam is reduced by 28.57-42.86%, and the floor is reduced by 70-80%. It shows that the degree of fracture development in coal and rock masses increases, the load-bearing capacity of surrounding rocks decreases, stress concentration is not easy to occur, and the pressure relief effect is good.

A good interaction between shields and roof strata is beneficial to the control of surrounding rocks in the open face area and the prevention of face-to-tip roof fall in fully mechanized caving face. In this paper, the finite element limit analysis and physical simulation are used to study the influence of the inclination of the shield canopy, the face-to-tip distance, the coal cutting height and the overlying rock rotation on the stability of the face-end roof and the interaction between the supports and surrounding rocks. The displacement development of the top coal both above the canopy and along the face-to-tip distance, the load condition of the support, the roof caving characteristics and the evolution of the face-end caving are obtained. The results show that: (1) the vertical displacement of top coal above the canopy presents the characteristics of "large in the middle and small at both ends". The horizontal displacement increases gradually from the canopy tip to the goaf direction, while the topcoal displacement in the non-support zone in the face-to-tip area decreases from the coal wall side to the canopy tip. (2) When the inclination of the canopy is 3° downward, the support can provide horizontal resistance to the top coal. The displacement of the top coal above the canopy and along the face-to-tip distance are more uniform. The stability of the model and loading condition of the support are also better. (3) The face-to-tip distance and cutting height are negatively correlated with the stability of the face-end roof. When the face-to-tip distance is 0.5 m, the top coal displacement is less than 45 mm, and the shield loading situation and model stability are better. When the cutting height is 3 m, the displacement of the top coal is small, which benefits the stability of the face-end roof. (4) The rotating failure of the overlying roof deteriorates the coupling relationship between the supports and surrounding rocks, reduces the available effective support resistance, and finally leads to the loss of stability of the face-end roof and the development of roof collapse in the face-to-tip area. Therefore, in the mining process of the long-wall top coal caving face, it is necessary to adjust the position of the shields and the coal cutting height in a reasonable manner, to reduce the face-to-tip distance by rapidly advancing the supports, so that the face-to-tip distance is minimized as small as possible.

In order to explore the development height of caving zone and water conduction fault zone under geological and mining conditions in Qinglongsi coal mine, comprehensive research methods of ground drilling, borehole loss observation method, color drilling TV imaging technology, empirical formula and analogy analysis are adopted. Height of overlying rock caving zone and water conduction fault zone in 5-20101 and 5-20105 working faces of the mine was measured and its particularity was analyzed. Results show that the maximum height of caving zone in Qinglongsi Coal mine is 9.7~17.0m, and the caving ratio is 4.1~7.4. The maximum height of the water-carrying fracture zone is 41.47~46.87m, and the fracture production ratio is 17.4~20.4. The advancing speed of the working face can affect the turning angle of the overlying strata and the formation of stable structure. The development height of caving zone and water conduction fault zone under the geological and mining conditions of the high-strength rapid advancing fully mechanized mining face is characterized by the large development height of the caving zone and the water conducting fracture zone.

It is the key for Heidaigou open-pit coal mine to realize sustainable, stable, economical and efficient mining to give full play to the advantages of overcasting blast-dragline overcasting mining technology in the combined mining system. With the principle of consistent advancing speed of combined mining system, the model between the production capacity of combined mining process and raw coal production capacity of Heidaigou open-pit coal mine is established. Based on that, with the goal to ensure the effective throw rate of overcasting blast and give full play to the production capacity of overcasting blast-dragline overcasting mining technology, through in-depth analysis of the restrictive relationship between overcasting blast bench height, height of expansion platform for dragline excavating and raw coal production capacity, then the relational model between the production capacity of the dragline overcasting system, the height of the overcasting blast bench, the height of the dragline expansion platform and the raw coal production capacity was established. It was determined that under the condition that the height of the overcasting blast bench was 45m, and the height of the dragline expansion platform was 13m~16m, the raw coal production capacity of the dragline overcasting operation area in the north of Heidaigou Open-pit Coal Mine could be 24.6199 million t/a~27.9865 million t/a, if the single bucket-truck operation area in the south of 500m developed normally, the entire open-pit mine can achieve a raw coal production capacity of 34 million tons/a.

At present,conventional low-alloy martensite wear-resistant steel plate is adopted in line pan deck plate and bottom plate of scraper conveyor, used at fully mechanized coal face at home and abroad. The service life of equipment is improved by increasing hardness. By adding a certain amount of Titanium, carbon and other elements to conventional wear-resistant steel plate material, after smelting, rolling, heat treatment and other processes, a large number of micron-size TiC hard particles are dispersed in conventional martensite matrix, which changes wear-resistant mechanism in the use of steel plate. When steel plate is worn out by abrasives such as coal gangue and quartz sand, TiC particles hinder the formation of grinding groove or make groove depth shallower, thus reducing steel plate worn out is achieved. The service life of equipment is prolonged and achieved without increasing equipment manufacturing cost. Through single test and comparison test under the same working conditions, the worn out rate of new wear-resistant deck plate of scraper conveyor for conveying million tons of coal is more than 1/3 lower than that of conventional conveyor, and the wear-resistance is significantly better than that of imported materials of the same hardness level, which provides solid technique support for improving the reliability of scraper conveying equipment and realizing safe and efficient mining of coal resources.

Intellectualization of coal mine is the core technical support for high-quality development of coal industry, and it is also a new stage of comprehensive mechanization, automation and digital development of coal mine. With the continuous integration and development of traditional mining engineering and the new generation of information technology, building a safe, intelligent, green and efficient coal mine is the strategic task and the only way for the high-quality development of Chinese coal industry in the new era. Shenmu Zhangjiamao Mining Co., Ltd. of Shaanxi Coal Group is a modern production mine with an approved capacity of 10 million tons/year. Building an intelligent management and control platform based on a set of standard system, three infrastructures (comprehensive perception network, big data center, resource view), eight intelligent application systems, and realizing comprehensive intelligent services in three business areas of “production, life, and ecology” are strategic tasks for enterprises to pursue excellent development and enhance core competitiveness. Combined with the development needs of intelligent coal mines, the main line is the design of the overall planning and comprehensive management operation platform of intelligent coal mines, the unmanned production system, the intelligent roadway excavation system, the environmental awareness and auxiliary system, and the construction of intelligent sites, and achieve research and development of key technology and equipment of Zhangjiamao Smart Coal Mine giant system and construction of demonstration mine. The information islands can be solved, intelligent mining capacity can improved, and data driven decision-making can be achived, which can realize the deep fusion of multi-source data in the whole mining area, and the multi-dimensional scene balanced comprehensive analysis and decision-making of collaborative optimization of production efficiency, security situation and business process, forming a new system of intelligent management and efficient collaborative operation in the mining area.

Based on the statistical data of coal mine accidents during 2016-2022, this paper uses mathematical statistics and charts to analyze the occurrence rules of coal mine accidents from four perspectives: grade, type,temporal and spatial distribution and 4M theory of accident causes. The results show that the key point of coal mine accidents is to reduce the general accident rate and the death rate of major accidents. Roof and transportation accidents are the key to control the total number of accidents, gas and water accidents are the key to control the number of deaths; There are more accidents in Shanxi and other energy-intensive provinces, while the southern provinces with complex geological structures are more prone to serious and major accidents. The key of accident prevention in underground working place is roadway, coal face and goaf. The highest number of accidents occurred in July and August and the highest number of deaths occurred in October to December; Accidents occur frequently from 8:00 to 16:00, and serious accidents are more likely to occur from 22:00 to 2:00 and 10:00 to 12:00. Illegal operation and other unsafe behavior is the main cause of accidents. The purpose of statistical analysis of accident occurrence rules is to provide reference for the safety production of coal enterprises and prevent coal mine accidents.

Based on the measured data of Inner Mongolia Shuangxin Mining Co., Ltd., using mining subsidence theory, numerical simulation, and other methods, the law and parameters of surface movement in shallow and multi-seam coal mining were studied. The observation data of surface movement under different conditions such as initial mining of upper coal and repeated mining of lower coal are summarized and analyzed. The results show that the initial period and active period of surface movement are relatively short, with the initial period of surface movement being about 0.5 months and the active period generally being 3-6 months; Due to the activation effect of the old goaf, the surface subsidence coefficient and the tangent of the main influencing angle significantly increase during the mining of the lower coal seam，The activation coefficient of the old goaf in the shallow and multi-seam mining of Shuangxin Mining Co., Ltd can be taken as 0.045~0.13; The damage of the overburden mainly includes shear damage and tensile damage. The surface is prone to discontinuous deformation such as ground fissures, and forms a wavy subsidence basin on the surface．

Aiming at the problem that the high temperature of deep coal seam will affect the deep in-situ artificial coal breaking technology, the long flame coal in Fuxin Basin of Liaoning Province is taken as the research object, and the coal sample is given multiple initial temperatures and subjected to liquid nitrogen cycle freezing and thawing. The physical and mechanical properties of coal sample structure damage are studied by the change values of joint width, overall pore volume and uniaxial compressive strength of coal sample surface after unloading. The mechanical model of high temperature coal freeze-thaw cycle is established to reveal the mechanism of temperature stress caused by liquid nitrogen freeze-thaw cycles on the structural damage of coal samples at different initial temperatures. The results show that the overall structure of coal samples with different initial temperatures has different degrees of damage after liquid nitrogen cycle freeze-thaw. The higher the initial temperature, the greater the temperature stress, the greater the deterioration of physical and mechanical properties of coal samples, and the shorter the macroscopic failure cycle. The research results can supplement and improve the fluidized mining technology.

Wire rope is an indispensable production machinery in coal mines. It is the main force-bearing equipment of the underground traction system. Accurate detection of wire rope defects and positions plays an extremely important role in safe production. The existing defect detection solutions have some deficiencies in the flexibility, accuracy and real-time performance of wire rope defect detection. In order to solve the above problems, this paper uses the camera to sample the wire rope before the well entry, and proposes an object based on YOLO V5. The surface small defect detection model realizes the accurate detection of small defects outside the wire rope. The transfer learning method is also introduced to improve the model accuracy of small sample training. After a large number of experiments, it is shown that in the task of wire rope defect detection, the average correctness rate and the average accuracy rate of the model are significantly improved compared with those before the modification, and the detection speed can be maintained at a real-time level.

Hydraulic cylinder operates under heavy and alternating load，which is very easy to produce fatigue damage. With the expansion of fatigue damage, fatigue strength gradually deteriorates, and even lead to weld cracking and exploding, affecting the supporting characteristics and causing safety hazards. The surface of weld is uneven, and it is difficult to detect by straight beam probe. The transducer is in-stalled on the wedge to detect. According to ray acoustic theory and Snell principle, the propagation path of ultrasonic wave in wedge and workpiece is determined, and the calculation formula of time delay rule of phased array with wedge is obtained. The impulse response of phased array transducer is obtained by superposing spatial impulse response of each element with wedge. The sound pressure on axis of different deflection angles is obtained by simulation, and the characteristics of the acoustic field are analyzed. The phased array experiment on the weld specimen with artificial defects is tested, and defects at different positions can be detected. The hydraulic cylinder weld of ZY9200/25/50D hydraulic support is tested on the spot. The positions and sizes of defects can be directly obtained from the image, and the acoustic field simulation can provide guidance for the testing parameters of ultrasonic phased array.

In order to improve the degree of automation of separating coal and gangue, the coal and gangue original image collected on site is used as input to establish a coal and gangue image recognition model based on convolutional neural network in this paper to solve the image feature values need to be manually selected and the robustness is poor. The convolutional neural network is visualized by deconvolution, and the process of extracting coal and gangue image features by convolutional neural network is analyzed. Decomposing the original image by biorthogonal wavelet, the wavelet transform layer is set up in the convolutional neural network. The convolution operation is performed by combining the high frequency coefficient with the original image to optimize the recognition effect of the model. The results show that this model can effectively differentiate the coal and gangue images and has strong generalization ability. Setting the wavelet transform layer can improve the network training efficiency and recognition accuracy. When combining the second layer high-frequency coefficient of wavelet transform with the original image, the network model is optimal. Compared with the traditional recognition model, the model has better adaptability under different illumination conditions, and the recognition accuracy of the test set reaches 93%.

Abstract：Low-rank power coal contains more fine-grained and clay minerals, which leads to its increased filtration difficulty. In this paper, anionic polyacrylamide (APAM) and cetyltrimethylammonium bromide (CTAB) were selected as filtration aids to enhance coal slurry filtration. Low-field NMR technique was used to detect the pore changes of the filter cake, and zeta potential meter, focused beam reflectometry, contact angle meter, surface tension meter and X-ray photoelectron spectroscopy were used to characterize the coal particles and filtrate properties. The results showed that the filtering aid improved the filtration rate and reduced the cake moisture, CTAB significantly improved the hydrophobicity of coal surface and reduced the surface tension of filtrate, but only increased the cake porosity by 2.65%, APAM significantly reduced the particle zeta potential and increased the floc size by about 7-9 μm, which increased the cake porosity by 11.65%. In summary, the mechanisms of APAM and CTAB to strengthen coal slurry filtration and dewatering are different, CTAB mainly promotes coal slurry filtration and dewatering by "lubricating" the pore wall of the filter cake and enhancing the hydrophobicity of the pore wall, while APAM mainly strengthens coal slurry filtration by weakening the electrostatic repulsive force between particles and promoting the formation of flocs to increase the pore rate of the filter cake.

The movement of particles on the screen surface will directly affect the screening efficiency of the screening equipment, In this paper, the discrete element method (DEM) is used to simulate the particle movement on the screen surface of the linear vibrating screen, the motion process and type of single particles on the sieve surface under different conditions were analyzed. The effects of vibration direction angle, amplitude and frequency on particle motion trajectory, collision period and collision interval were analyzed. The results show that the amplitude is in the range of 10mm~40mm, and the collision period and collision interval gradually increase with the increase of amplitude. The frequency is in the range of 3Hz~7Hz, the collision period and collision interval first increase and then decrease, when the frequency is 6Hz, the collision period and collision interval are the largest. When the vibration direction angle is 20°, 30°, 50°, 70°, the particles on the screen surface have sliding motion, and when the vibration direction angle is 80°, 90°, the particle collision period does not change, and increasing the vibration direction angle will reduce the collision interval of the particles. In most simulation cases, the particles are densely located in the first few collisions of the sieve surface, and the porosity can be increased in the area with dense landing points according to the simulation results and actual production experience when the sieve surface is opened.

Virtual and real mapping and visual monitoring of digital twin are the effective means to realize mine intelligence. OPC UA based digital twin mine lifting system information model construction method is proposed for its various subsystems, complex equipment types and heterogeneous data sources. First, the digital twin data integration architecture based on OPC UA is established, and the information model of the mine elevator system is constructed according to the OPC UA information model modeling rules. Then, the XML description file is generated through the modeling tool UaModeler, and the structure data of the information model and the attribute set are mapped in the OPC UA address space by building the OPC UA server. Finally, the information model was tested by using the OPC UA client tool UaExpert connection server. The results show that the information model of the digital twin mine lifting system based on OPC UA can realize the virtual and real mapping of multi-source heterogeneous data, obtain the information model structure and object data, and display and prove the effectiveness of the information model on the digital twin visualization platform in real time, provide data interaction service for the digital twin system of the mine upgrading system, and realize the state monitoring and fault early warning of the mine lifting system.

In order to improve the accuracy of coal mining machine rocker gear fault diagnosis, reduce the model size and facilitate the deployment to more mobile and edge devices, a lightweight densely connected convolutional network (LW-DenseNet) based coal mining machine rocker gear fault diagnosis model is built. Separable convolution is used instead of traditional convolution to reduce model parameters and improve diagnosis efficiency; feature propagation is enhanced by dense connection mechanism to strengthen feature extraction capability. The rocker arm gear vibration signals collected from the coal mining machine rocker arm loading test bench are used to train and verify the effectiveness of the model. The experimental results show that the proposed method can achieve 99.276% classification accuracy with only 0.05MB model size compared with various diagnostic models, and the good generalization of the model is verified using the Case Western Reserve University bearing dataset. Finally, the visual representation of the key layer using t-SNE clearly shows the good feature extraction performance of the model.