In order to explore the deformation and failure law of roadway surrounding rock under different coal pillar widths during roadway excavation in three-soft coal seam under the influence of adjacent goaf, the research methods of theoretical calculation, numerical simulation, physical similarity simulation and field measurement are used to analyze the stress evolution law, plastic failure range and displacement distribution characteristics of roadway surrounding rock under different coal pillar widths after the existence of goaf. The results show that the free zone is the main reason for the asymmetric failure after roadway excavation, which increases the angle between the principal stress direction and the vertical direction of the coal pillar, and the stress of the two sides of the roadway is asymmetric distribution characteristics that the coal pillar side is greater than the solid coal side. The failure form of three soft roadway is mainly shear failure, and the main body of failure is two sides. With the increase of coal pillar width, the angle between principal stress direction and vertical direction decreases, and the failure degree of roadway surrounding rock decreases. The influence degree of free area on different positions of roadway is different. The failure degree of surrounding rock in the middle of roadway is greater than that at the end, and the failure degree of coal pillar side is greater than that of solid coal side. The increase of the width of the coal pillar has limited improvement on the stress of the surrounding rock and the damage of the coal pillar. The field results show that when the width of the coal pillar is 20 m, the normal maintenance of the roadway meets the demand.

This paper summarizes the current situation of the technology and equipment supporting technology of single-lane driving, double-lane driving and large-section cut through in Shendong Coal Mine. Expounds the intelligence of the imported digging-anchor integrated machine, the intelligence of the imported continuous miner, Inertial navigation technology of intelligent anchor digging machine, complete set of intelligent tunneling technology, the near-end AI recognition and remote cloud control technology. Discusses the auxiliary equipment and technology, such as embedded hole drilling robot, intelligent pipeline snatch equipment, intelligent explosion-proof diesel slotting machine, automatic cable retracting vehicle, intelligent warehouse cleaning robot, etc. Analyzed the characteristics of using flexible formwork support to reduce tunnel excavation in Shendong Coal Mine and retaining tunnels along the goaf，which have been applied in 24 working faces, the total length of the entry retaining is up to 40000 m, which greatly reduces the amount of roadway excavation and alleviates the tense situation of continuous mining in the mine. It is proposed that Shendong Coal Mine should speed up the promotion of the integrated production process of excavation and anchor, use 5G technology to play a technical security role, adopt a transparent geological security system, improve the excavation efficiency and reduce the safety risk. It is still necessary to deepen the technical innovation of tunneling technology, and make great efforts in the promotion and implementation of flexible formwork support technology for retaining roadways along the goaf. It is also necessary to solve the key problems of autonomous control, intelligent interconnection, security and credibility of intelligent devices from the root.

Coal engineering projects have the characteristics of complex design process and long construction period. Coal design institutes are facing severe problems of transformation and development. The early design stage is extremely important in the whole process of coal engineering construction. It is necessary to improve the quality and quality management ability of coal design institutes. This paper takes the project of Z Coal Design Institute as the research object, analyzes the factors affecting the design results, and analyzes the index factors affecting the design quality from the aspects of human, machine, material, method and environment based on the project quality management theory, method and related standards and norms, combined with the 4M1E method. The analytic hierarchy process is used to construct the hierarchical evaluation model, and the model is evaluated and analyzed, and the countermeasures and suggestions for design quality optimization are put forward, including strengthening design team management, technology construction, strengthening information management and hardware support, and strengthening design quality management system.

Niaoshan Coal Mine introduced fully mechanized top coal caving and gob-side entry retaining technology during the mining process of 11031 working face. Mineral pressure of working face and deformation law of surrounding rock of roadway. Theoretical analysis and calculation, mine pressure monitoring analysis and research show that the optimal depth of pre-split slit is 14.0 m, and the slit angle is 20°. During the construction period, the moving amount of roof and floor was finally stabilized at 79 mm, and the moving amount of the two sides was stable at 87 mm. The deformation of the roadway was small, and the average pressure of the 110 method area (the side of the cutting seam) was lower than that of the 121 method area (the side away from the cutting seam). 25.1%, and achieved good results, filling the gap of gob-side entry retention technology for roof cutting and pressure relief in Niaoshan Coal Mine.

In response to the problem of larger deformation in roadway advanced of working face, the influence of the movement characteristics of the overburden structure to deformation of the advanced roadway at the end of the working face was studied. The mechanism of roof cutting and pressure relief of the advanced roadway and the key parameters of roof cutting were analyzed, and the field test was carried out. The results show that the root cause of the deformation of the advanced roadway in the working face was the downward movement of the arc triangle roof. The weight and loading acting on the roof of the roadway during the advancing process of the working face. The advanced and lateral stress concentration were the intermediate processes. Reasonable cutting thickness and cutting angle can effectively cut off the linkage effect between the roof above the roadway and the roof of the working face, and cut off the tendency transfer of the advanced pressure. After the application of the research results, the single roof support was canceled in the advance roadway. Compared with that before unloading without roof cutting, the cumulative deformation of roof and floor was 1/5 of the original, and the cumulative displacement of two sides was 1/3 of the original.

In order to solve the problem of floor heave of deep well in soft rock roadway with high stress in Linxi Mine, the mechanical mechanism and control technology of floor heave of deep well in soft rock roadway with high stress were studied and analyzed by combining theoretical analysis and field measurement, and the following conclusions were drawn:1) The calculation formula of ultimate failure depth, ultimate failure width and effective sliding force along the sliding surface of both sides of the roadway were deduced; 2) It was judged that the floor failure of return air lane of 1791-2 working face of Linxi Mine will be the form of extrusion flow floor heave and full section failure bulge;3) The floor heave mechanism, the cause of floor heave and the control way are analyzed; 4) The floor heave control technology of "roof, wall and floor under the same control" was proposed. The roof and two sides of roadway were supported by high-strength prestressed anchor bolt net + anchor cable, and the bottom plate was reinforced by prestressed anchor cable anchoring + concrete bottom laying technology; 5) The field industrial test showed that the floor heave of the roadway had been effectively suppressed and can meet the requirements of normal use. The research of this paper can be used as reference for similar projects.

In view of the uneven spacing between the underlying mining roadway and the overlying goaf in the extremely close coal seam, it is easy to have sparse or excessive support when adopting a support scheme. Based on theoretical analysis, numerical simulation, field test and other research methods, combined with the measured geological conditions, the air roadway in the experimental section is divided into three areas according to the layer spacing: greater than 6.0m, 4.0m ~ 6.0m, and less than 4.0m. According to the superimposed beam theory, the minimum effective anchor layer thickness of the roof of the mining roadway is obtained to be 3.51M, and the feasibility of bolt support in the underlying coal roadway is analyzed; Three support schemes are proposed for different layer spacing in three areas, and are tested by numerical simulation and applied in field engineering. The results show that after adopting targeted support in different areas, the surrounding rock is relatively stable, the surrounding rock deformation of the roadway is reasonably controlled, and the overall deformation of the roadway is small. The subregional support technology effectively controls the surrounding rock deformation of the underlying roadway, ensures the safe production of the mine, and reduces the cost of the enterprise.

To explore the advanced support technology for large section gateroads, with the main transportation haulage roadway of 31205 working face in Cuncaota No. 2 Mine as the engineering background, a combination of on-site investigation, theoretical mechanics analysis, and FLAC numerical simulation was used to analyze the feasibility of replacing single hydraulic props with active advanced support. Based on the mechanism of active advanced control, a technical scheme of advanced support for reinforcement in the center of the roof was proposed. Field monitoring indicated that the maximum displacement of the roof, floor and two sides under active advanced support were 21mm and 23mm, respectively. According to the monitoring of anchor rod force, the anchor rod of active advanced support can be timely loaded. Moreover, the visual results showed that the integrity of the surrounding rock was good, which verified the feasibility of the scheme. This technology can meet the requirements of safe and efficient production, and promote the intelligent development of working face.

There are problems such as high stress concentration, large deformation, and difficulty in support in the goaf under the hard roof. Taking the 21105 working face of Hulusu Coal Mine as the engineering background, the breaking law of the overlying roof during the mining period of the working face under the hard roof is analyzed, the deformation mechanism of the surrounding rock of the goaf is studied, and the control method of "roof drilling and blasting+coal pillar hydraulic cutting" pressure relief in the goaf is proposed, The stress distribution law of the surrounding rock of the goaf roadway before and after pressure relief was simulated using FLAC3D software. After adopting the pressure relief measures of "roof drilling and blasting+coal pillar hydraulic cutting" in the return air roadway of the 21105 working face of Hulusu Coal Mine, the peak stress at the deep base point of the coal pillar decreased by 36.1%, the peak stress at the shallow base point decreased by 19.1%, the daily average energy of microseisms decreased by 67.0%, and the daily total energy of microseisms decreased by 35.7%. Moreover, the occurrence of high-energy events was significantly reduced, and the deformation of the roadway was effectively controlled. The experimental results show that the control technology of "roof drilling and blasting+coal pillar hydraulic cutting" for pressure relief in the goaf roadway can effectively reduce the stress of the coal pillar, reduce the deformation of the roadway, and provide a new governance method for controlling the strong rock pressure behavior of the goaf roadway under the hard roof slab.

In order to study the mechanism of rock burst during the gob-side roadway driving of small coal pillars under the condition of thick and hard roof in hujirt mining area, the stress distribution model and flac3d numerical model during the roadway breakthrough gob-side roadway were established based on the mine pressure behavior during the penetration of 11-3107 gob-side roadway in Menkeqing Coal Mine. The stress evolution characteristics of heading face at different distances from the roadway breakthrough point were compared, and the mechanism of rock burst during the roadway breakthrough of gob-side roadway was revealed. The deformation of roadway surrounding rock and coal body stress were measured by means of cross distribution method, stress, micro seismic and other monitoring methods. Based on mechanism analysis and field measurement, the integrated technology of pressure relief and support is proposed. The results show that due to the existence of thick and hard rock strata above the roof of the coal seam, after the excavation of the roadway, the thick and hard rock strata act on the surrounding rock of the roadway through stress transfer, resulting in large deformation of the roof, floor and side of the roadway lagging behind the drilling head. With the closer distance between the drilling head of the roadway and the roadway breakthrough point, the deformation of the roadway gradually increases. Through the increase rate of the deformation of the roadway, it is clear that when the distance from the penetration point is about 160 m, the deformation of the roadway begins to increase sharply. The microseismic events are mainly concentrated in the roadway roadway breakthrough area within 190 ~ 60 m from the roadway breakthrough point, and the theoretical calculation is consistent with the field mine pressure appearance.

Considering the low intelligence level of the existing step-by-step self-moving tail equipment in fully mechanized roadway and the lack of research on intelligent control technology, the intelligent control technology is studied. According to the structural characteristics, working principle and working conditions of the self-moving machine tail and the requirements put forward by the intelligent coal mine acceptance method issued by the state for the intelligent tail of the belt conveyor, this paper puts forward the overall design scheme of the self-moving machine tail control system. The software and hardware systems are designed for one-button self-shift control technology, multi-machine linkage control technology and personnel approach identification and intrusion early warning technology. The intelligent control technology of self-moving tail studied in this paper is applied to the heading face of 31107 transportation trough in Halagou Coal Mine of Shenhua Group Shendong Coal Co., Ltd., and more than 1000 meters of driving operation is successfully applied, and the field use is good. The intelligent control of self-moving tail can be realized. The personnel approach identification and intrusion early warning technology studied in this paper can accurately locate the people around the tail of the self-moving machine, and the posi-tioning error is less than 30cm, and can identify the personnel after entering the dangerous area, which improves the safety of the self-moving tail equipment. The research results of this paper can provide support for the in-telligent construction of underground heading face in coal mine.

Aiming at the problems that multiple motors in the traditional pressure system cannot cooperate and the pressure room needs regular inspection, an intelligent pressure system is designed. By adding programmable control cabinet to the control side and introducing fuzzy control algorithm, the functions of press air supply, load balancing and automatic rotation of the air pressure system are realized. Through the fault diagnosis device and video analysis camera to realize the monitoring of equipment and personnel, to ensure the safety of people and things. The control platform of the intelligent compressed air system displays various data of the compressed air fan and displays the analysis results. The application of this system reduces the waste of electric energy, provides accurate diagnosis results, and improves the level of intelligent coal mine.

Gas extraction activities will change the stress distribution of coal and rock mass, leading to the expansion and development of cracks in coal and rock mass until failure, and the occurrence of high frequency micro-fracture signal of small magnitude.The microseismic monitoring technology can be used to identify the micro-fracture signal effectively, monitor the pumping process in real time, and detect geological anomaly areas and hidden structures. Under the influence of gas extraction at 15240 working face, the number of single-day microseismic events increases exponentially (2-12 times) and the time series is continuous in a certain spatial area far from the mining line, and this area is identified as a geological anomaly area under the influence of gas extraction. The response characteristics of microseismic data were summarized by analyzing the evolution characteristics of temporal and spatial series, vertical disturbance range and energy in space. With the continuation of gas extraction time series, the activity of microseismic events in geological anomaly areas changed from strong to weak, and the spatial distribution presented a "central-distributed" evolution trend. The proportion of roof 0 ~ 5 m is significantly higher than that of normal stoping stage, and the proportion of floor 5 ~ 15 m is large. The energy of microseismic events shows an irregular U-shaped distribution, and the overall energy increases 3~8 times compared with the recovery data,attention should be paid to strengthening hydrogeological observations.

To solve the serious problem of perimeter rock deformation and ring breaking in the field by mining influence, we take Shanxi Jincheng Coal Mine as the engineering background, analyze the different stages of the overlying rock movement law along the perimeter of the perimeter of the perimeter of the perimeter of the perimeter of the mine, clarify the focus of the control of the perimeter rock, and determine the synergistic control way of "internal support-external pressure relief", and use the theoretical analysis, on-site application and monitoring. Theoretical analysis, field application and monitoring were used to analyze and validate the flexible concrete support next to the lane and the roof plate pre-cracking and pressure relief by over-blasting. The research results show that the deformation speed of the roadway along the hollow stay roadway is larger within 100m of the lagging working face, and the pressure change of the flexible mold wall is larger and reaches the highest value within 200m of the lagging working face, so it should be the key point of maintenance; the optimized roadway support body can meet the bearing capacity of the roadway gangs; the roadway support of the flexible mold concrete wall and the over-the-top pre-cracking cutting and unloading of the roof work synergistically to reduce the impact of mining stress, improve the mining stress, and reduce the impact of the mining stress, improve the mining stress, improve the mining stress, and improve the mining stress of the roof. Mining stress influence, improve the stress environment of the stay lane at the same time improve the support strength of the lane gang support strength, effectively improve the stability of the stay lane perimeter rock.

The failure characteristics of overburden in close seam group mining are different from those in single seam mining, and there are problems of interlayer influence. Taking the coal seam 11#, 14-2# and 14-3# in Yanzishan Coal Mine of Jinneng Holding Coal Industry Group as the research object, through the physical similarity simulation experiment and numerical simulation calculation, the overburden failure characteristics and stress transfer rule of the surrounding rock of the top and floor during the mining of the close coal seam group are studied and analyzed. The research results show that with the increase of mining frequency, the lateral crack development and vertical crack penetration effect of the roof are more obvious, the caving block degree decreases obviously, and the pressure law is not obvious. The stress peak value of coal seam roof overlying rock due to mining decreases with the increase of mining frequency. Under the influence of the first mining, the overburden stress after the stabilization is obviously smaller than that of the original rock, while the overburden stress after repeated mining stabilization is similar to that before the mining. Under the influence of multiple mining movements, the overlying strata are destroyed more thoroughly, forming a stepped cut. The research results can provide reference for the control of surrounding rock, water accumulation and gas control in goaf in close proximity coal seam groups with similar conditions.

As an important facility in the mine, the long-term stability of the surrounding rock in the permanent chamber of the mine is crucial for the safe production of the mine. In response to the technical problem of instability and difficult control of large deformation of the surrounding rock of the central auxiliary water chamber in Yidong Coal Mine, the deformation and failure characteristics of the surrounding rock of the auxiliary water chamber on site were sorted out, a UDEC numerical calculation model was established, and the stress, crack development degree, and deformation and failure characteristics of the surrounding rock of the chamber under the original concrete arch support were analyzed. The deformation and failure mechanism of the surrounding rock of the auxiliary water chamber was comprehensively analyzed. The results indicate that the main reasons for the difficulty in controlling the large deformation of the surrounding rock are low original support strength, uncoordinated support system, and expansion of the bottom plate when encountering water. Based on the actual on-site conditions and numerical simulation inversion results, a combined support technology of "grouting reinforcement + anchor bolt, cable + reverse arch" is proposed for repair practice. On site monitoring shows that within 45 days after repair, the maximum convergence of the two sides is 55.8mm, and the maximum displacement of the top and bottom plates is 46.5mm, which meets the requirements for safe use of the auxiliary water chamber and ensures safe production in the coal mine.

In this paper, the research method of combining theoretical analysis and field measurement is used to study the active advanced support technology with anchor rope and field application in the advanced section of the main haulage roadway of 12403 large mining height working face in Shangwan Coal Mine.Based on the active advanced support technology of anchor cable, the support mechanical model of main haulage roadway in fully mechanized mining face is established. The influence range of advanced support pressure and the support strength of bolt ( cable ) and surrounding rock in main haulage roadway under the condition of 8.8 m large mining height are checked.This study provides theoretical support for solving the problem of advanced support such as strong dynamic pressure and large deformation.The following conclusions are obtained by pressure monitoring:In the initial stage, the pressure of the anchor rod in the main transport roadway is basically maintained between 40 ~ 50 kN, and the pressure of the anchor cable is basically maintained between 50~60 kN. Starting from the position 45 m away from the working face, the force of the anchor rod and the anchor cable begins to increase slowly, but the growth rate is small ; from the position of 20 m away from the working face, the stress of anchor rod and anchor cable increases greatly.The stress of bolt and anchor cable tends to be stable after the cumulative increase of 15~25 kN. The average influence range is about 42 m, and the average stress concentration factor is 1.4.The deformation of surrounding rock began to appear when the measuring point was within 45 m from the working face, but the early deformation was small.With the continuous advancement of the working face, the deformation of the surrounding rock gradually increases.When the distance between the station and the coal wall is less than 30 m, the deformation growth rate is larger, but the surrounding rock is stable and the deformation is controllable. The statistical results of borehole peep show that the overall development degree of surrounding rock cracks in the advance support section of the main transport roadway is low, and the integrity of surrounding rock and coal seam is good. The advance support method of anchor cable has a good support effect on the surrounding rock of the roof.

In order to study the effect of shear force and axial load on reflected signal characteristics in complex rock strata, the box dimension and stress wave property parameters of fractal dimension are applied to nondestructive testing. The effect of different dynamic load on the same specimen and different shear force on the stress wave behavior was studied by loading different concentrated loads in the middle of the free end of the bolt. MATLAB software was used to calculate the box dimension of the detection signal, and the changing law of the box dimension under different circumstances was summarized. The amplitude, effective value, standard deviation and amplitude frequency of the detected signal are analyzed to judge the signal strength and its rule. The results show that the signal strength decreases gradually with the increase of the axial load of the anchorage structure and the free end shear of the anchor bolt. The shear force affects the ultimate bearing capacity of the bolt. With the gradual increase of shear force, the box dimension will increase, and so will the ultimate bearing capacity of the anchoring structure. With the increasing of axial load, the box dimension first increases and then decreases, and the anchorage structure fails at the maximum box dimension.

The sealing quality of extraction drilling holes is closely related to the grouting pressure. In order to study the sealing quality of each bedding borehole under different grouting pressures, the 2214 working face of Liujialiang coal mine of Xuangang Coal Power Co., Ltd. was taken as the test object. First, according to the actual occurrence of the coal seam, COMSOL numerical simulation software was used to simulate the diffusion range of slurry in the coal seam under different grouting pressures. The results show that within the range of 1-4MPa grouting pressure, The diffusion radius of the slurry in the coal seam is positively related to the grouting pressure, while the increase of the diffusion radius of the slurry is inversely related to the grouting pressure; Secondly, under the condition that the initial sealing depth, sealing length and other sealing parameters are fixed, the on-site borehole sealing test is conducted according to the four grades of 1MPa, 2MPa, 3MPa and 4MPa, and the sealing quality of each extraction borehole is evaluated and compared by using the air leakage rate. The field test shows that there are 4 and 2 drill holes with 1MPa and 2MPa grouting pressure, and the average air leakage rate is 32.76% and 28.65% respectively, while there is no air leakage in the drill holes with 3MPa and 4MPa grouting pressure; The numerical simulation and field test results show that the reasonable grouting pressure is 3Mpa when drilling and sealing holes along the working face.

The pore structure characteristics of coal are closely related to gas absorption and transport. Due to damage caused by structural stress, the pore structure characteristics of tectonic coal tend to be complicated. Thus, investigating the development of tectonic coal pores is an important direction for improving the gas treatment level. In this paper, three groups of tectonic coal and a group of intact coal from the Dongyu Coal Mine in the southern part of the Xishan Coalfield were taken as the research object. Besides, the pore characteristics of tectonic coal and intact coal were jointly observed using a low-temperature liquid nitrogen adsorption method and scanning electron microscopy (SEM). As shown by research, the nitrogen adsorption amount of the three groups of tectonic coal was 2.04 times, 1.49 times, and 2.90 times that of intact coal. The pore volume of the three groups of tectonic coal was 2.08 times, 1.53 times and 2.96 times that of intact coal, respectively. The pore volume of the three groups of tectonic coal in micropore and small pores was more than 69.71%. The proportion of micropores in the pore specific surface area of the three groups of structural coal exceeded 79.04%. The micropores and micropores of intact coal provide 89.38% of the pore volume, and the pore specific surface area of micropores accounts for 93.97%. The pore structure of the three groups of tectonic coal was more complex than that of the intact coal and had larger fractal dimension (2.6985 to 2.7106). The fractal dimensions of three groups’ tectonic coal (10,000 times) were 1.962, 1.979, and 1.947, respectively, greater than that of intact coal. In comparison to intact coal, tectonic coal had more developed pore characteristics; the fractal dimension D1 was directly proportional to the total pore specific surface area and microporous surface area. The volatile content was directly proportional to the total pore surface area, microporous surface area, and small pore surface area within a certain range.

Due to the harsh service environment and complex stress state, mining drill pipe is prone to failure. This will seriously affect normal production and worsen the accident due to salvage difficulties.In this study, the force analysis of drill pipe joints was conducted on Φ73 mm outer-flat directional drill pipes in coal mines under different loads. The mechanical property parameters of the joint material were obtained through uniaxial tensile tests, and the constitutive model of the joint material was constructed. then, the elastic-plastic finite element analysis model of the drill pipe joint thread was established by applying the virtual work principle, Von Mises yield criterion, and contact nonlinear theory to analyze the stress state and stress field distribution of the joint under the action of load under different working conditions. The study demonstrates that the drill pipe joint exhibits satisfactory sealing performance and connection strength at a preload torque of 2000 N?m. The first thread tooth near the main shoulder is identified as the primary failure site under both single torsion and tension torsion loads. Meanwhile, the main shoulder is the principal failure location under compression, bending, and torsion loads. Moreover, under the combined effect of the maximum torque and thrust of the drilling rig, the joint's bending resistance is found to reach 3°/3m.

To improve the dynamic reliability of the transmission system of the mine equipment, the meshing dynamic model was established based on ADAMS, the kinematic characteristics and meshing force of the gears were analyzed, and the influence of the speed and load on the transmission stability and the load sharing characteristics of the planetary gear was discussed. The results show that the transmission stability of the first stage planetary gear train is worse and the eccentric load is more serious than that of the second stage planetary gear train. Besides, as the increase of load, the speed fluctuation of the first stage planetary gear intensifies and the load sharing performance weakens, but the load sharing performance of the second stage planetary gear is slightly improved. Furthermore, with the increase of rotating speed, the speed fluctuation of the planetary gear intensifies but reduces of the central gear, and the load sharing performance of the internal mesh of the first stage planetary gear is relatively improved. The results provide a reference for revealing the fault mechanism and optimizing its transmission performance of the transmission system of the mine equipment.

In order to address the problems that arise when a single-phase ground fault occurs in the current mine grounding power supply system, this paper proposes a line selection method based on parameter optimization variational mode decomposition (VMD) combined with the thorough component of ze-ro-sequence current. These faults are caused by the difficulty of extracting signal features from the arc suppression coil and the significant influence of noise signal. In this method, the whale optimized VMD is used to decompose the zero-sequence current signal, and the fault line is identified according to multiple criteria of non-power frequency component signal energy, power frequency component signal polarity and waveform correlation. Using RTDS/RSCAD to build a mine power supply system model, simulated and tested different fault conditions, including fault grounding resistance, fault ini-tial phase angle, and fault point location of different fault lines. The results show that this method has a more intuitive line selection effect under the premise of ensuring accuracy and reliability, regard-less of the fault conditions.

The propagation of electromagnetic waves in underground media is complex. Studying the impact of coal (rock) layers and geological anomalies on the perspective of electromagnetic waves enables more accurate inference and interpretation of anomalous bodies. In this paper, a three-dimensional numerical simulation method is used to simulate the propagation characteristics of electromagnetic waves emitted by a circular antenna in coal (rock) layers encountering different types of geological anomalies (faults, subsidence columns) under full-space conditions. The following conclusions are obtained: (1) When the anomalous body is predominantly filled with air, it has a small absorption coefficient, low electromagnetic wave loss, and the contour lines of magnetic field intensity protrude outside. When the anomalous body is predominantly filled with water, the absorption coefficient increases, resulting in greater electromagnetic wave energy loss and concave curves. When filled with other media, the electromagnetic wave loss is between the two extremes, and the electrical characteristics of the anomaly area can be determined by observing the changes in field strength curves and contour lines. (2) Different shapes and sizes of anomalous bodies result in different distributions of magnetic field intensity. When the anomaly area is circular or approximately circular, the magnetic field intensity is distorted within the anomalous body and gradually returns to a normal distribution away from the anomaly, making identification more difficult. The smaller the diameter of the anomalous body, the more challenging the identification becomes. When the anomaly area consists of a linear fault, the angle between the fault direction and the tunnel affects the number of affected measurement points, making identification easier when the angle is small. As the angle increases, fewer measurement points are affected, making identification more difficult, and the fault direction can be roughly determined based on this observation. (3) Under normal circumstances, the field strength curve exhibits a symmetrical parabolic shape with the highest intensity in the middle and gradually decreasing on both sides. However, the shape of the curve varies depending on the position, morphology, and filling material of the anomalous body. When the anomalous body is large, the symmetry of the curve is disrupted, resulting in a symmetrical or asymmetrical "M" shape. Therefore, in the initial stage of data processing, the qualitative characteristics of anomalous bodies can be preliminarily determined by identifying the shape of the curve. However, precise localization of anomalous features along the ray requires further analysis using tomographic imaging to achieve a correct and reasonable understanding.

Surface roughness directly affects the mineral surface and water action and plays an important role in the flotation of minerals. There are many studies on the relationship between mineral surface roughness and wettability, but the results are not uniform. In this study, a series of coal flakes with different surface roughness were prepared using sandpaper of different grit sizes and their surface properties were characterised using, for example, contact angle and interaction force measurements. The effect of roughness on the surface wettability of the coals was analysed with the aid of the Wenzel wettability model. The contact angle results show that the contact angle decreases with increasing surface roughness of the coal sample, indicating an increase in hydrophilicity of the coal surface, which may be due to the surface microstructure making it easier for water molecules to enter the surface defects. Spreading and residual force measurements showed that the spreading and residual force of water droplets on the coal surface increased as the roughness increased. As the roughness increased from 0.32 μm to 2.38 μm, the droplet spreading force increased from 159.00 μN to 209.60 μN and the residual force of the droplet increased from 20.74 μN to 23.64 μN. The contact angle and force measurements were consistent, meaning that increasing roughness increased the hydrophilicity of the coal surface and had a detrimental effect on flotation separation.

Abstract:In response to the problem of high surface oxidation degree, high oxygen functional groups, and low yield and high ash content of flotation clean coal in the Luotuoshan Coal Preparation Plant of Wuhai Energy Company, the physical and physicochemical properties of oxidized coal slime were analyzed using elemental analysis, industrial analysis, particle size composition analysis, scanning electron microscopy, and XPS analysis and testing methods. The flotation effect of oxidized coal sludge was compared with that of diesel oil, conventional polar trapping agent and new polar-non-polar composite trapping agent independently developed by the laboratory of the research group, and the parameter optimization of the conditions of the trapping agent and foaming agent was carried out by using the one-way test method. The contact angle test and adsorption test method were used to reveal the action mechanism of the new polar-non-polar composite trapping agent to strengthen the flotation effect of oxidized coal sludge. The mechanism of the new polar-nonpolar composite capture agent to enhance the effect of oxidized coal slurry flotation was revealed. The results show that the flotation of oxidized coal sludge using diesel and conventional polar traps has poor flotation effect, and it is difficult to meet the production requirements; while the flotation of oxidized coal sludge using the new polar-non-polar composite trapping agent has better effect, and the agent is easier to be adsorbed on the surface of oxidized coal sludge, and it significantly improves the contact angle of the surface of the sludge, reduces its wettability to water, and thus enhances the flotation effect of the oxidized coal sludge. At the same time, the flotation of oxidized coal slurry with the new polar-nonpolar composite collector , when the total dosage of the collector is 1200g/t, the yield of refined coal can be up to 74.28%, and the ash content of refined coal is only 7.66%.

The complex occurrence conditions of steeply dipping coal seam affect the safety and stability of the support. At present, the most critical problem facing mining with large dip Angle working face is to ensure the stable work of the support. Based on the analysis of mechanical behavior of φ160/105-730 bedload jack in a large dip coal seam, and the bidirectional transient fluid-structure coupling analysis of bedload jack with the help of ANSYS Workbench software, this paper obtains the stress and strain characteristics of the bedload jack of hydraulic support. Combined with the actual working conditions, The analysis shows that the failure of the cylinder water flowing of the push jack is easy to occur at the junction of the piston rod and hydraulic oil and the push jack cylinder block. The thickness of the cylinder block at the junction of the piston rod and the cylinder block should be properly thickened, and the seal at the junction of the piston rod and the cylinder block should be strengthened, which provides a guarantee for the stability of the hydraulic support and the safety of the coal mining space on the large Angle working face.

The problems and challenges faced by the expandable belt conveyor in the design optimization, fault diagnosis, intelligent operation and maintenance of key components for the underground working face of coal mines. Starting from the key technologies such as efficient disassembly, integrated drive, intelligent control and intelligent monitoring, this paper puts forward the key technologies of the intelligent permanent magnet integrated driving pulley non-foundation telescopic belt conveyor. It mainly involves four aspects: there is no foundation for the telescopic belt conveyor and the highly efficient dismounting technology; Mining high-power permanent magnet integrated driving pulley technology; Intelligent permanent magnet frequency conversion tensioning technology; Intelligent monitoring technology for coal mine belt conveyor. Through the above technologies, the safe, efficient, and intelligent operation of the expandable belt conveyor can be ultimately achieved, providing equipment support for the intelligent construction of coal mines in the coal industry.