In order to solve the safety problem of fully mechanized caving mining under the compound water body composed of goaf and ground subsidence water, the II3 extra-thick coal seam in the first mining area of Linglu Coal Mine is faced by the II2-1 coal seam mined water and ground subsidence water. Take the mining under the composite water body as an example. Using the method of combining engineering analogy and theoretical analysis, the damage height of the overlying strata in fully mechanized caving mining, as well as the height of the coal and rock pillars for waterproof, sand control and collapse prevention are calculated; The difference between the distance between the water area and the mining coal seam and the height of the safe coal rock pillar, using the Kriging difference method to draw three maps of the influence of the water in the goaf on the water filling, sand break and collapse prevention of the mining coal seam. Comprehensively analyzed the threat of the roof composite water body in the first mining area II3, and finally evaluated the safety of fully mechanized caving mining under the composite water body. The research results show that: mining in a mining area can meet the requirements for water-proof and safe coal and rock pillars in surface subsidence water; fully-mechanized caving mining in extra-thick coal seams under surface subsidence water is safe; combined geophysical prospecting and drilling to determine the mined-out area volume After the water has been drained, the safe mining of the submerged water in the goaf can be realized; after the composite water body is taken to leave safe coal and rock pillars, combined with geophysical and drilling, and carry out comprehensive water prevention and control measures such as drainage of the water in the goaf, Fully mechanized caving mining under complex water bodies is safe and feasible.

In view of the problems of gas prevention and control, production cost and connection during stoping in the multi-entry arrangement of fully mechanized caving face in Baode County coal mine, the optimization scheme of roadway layout and the ventilation of working face and gas drainage in Goaf based on this condition are put forward, through the comparison and analysis of technology and economy, the layout of the roadway and the gas control method during the working face stoping are determined and perfected, the field test proves that the optimization scheme is reasonable and feasible, and its safety, economic and social benefits are obvious before the optimization. The optimization scheme of roadway layout has been popularized and applied in Baode County coal mine. Based on the good effect of gas prevention and control after optimization of roadway layout in fully mechanized caving face in Baode County coal mine, it can provide a useful reference for roadway layout and gas prevention and control in fully mechanized caving face under similar conditions.

In the process of coal mining, it is inevitable to produce a large number of gangues, which not only occupy the land, but also cause great damage to the surface ecological environment. In order to solve a series of problems caused by gangue discharge, Shendong mining area starts from the source of mining design, through optimizing the roadway design and equipment matching to reduce the generation of gangue at the source, the gangue that can be separately loaded and transported in the underground is discharged through the construction of the special gangue discharge roadway in the underground, and these gangues are reused in the underground engineering, realizing the zero rise well of gangue in the underground. Through the implementation of the above measures, the technical problems of environmental pollution caused by underground waste disposal and waste discharge are solved.

Abstract：The research and application of intelligent dry separation system in coal mine is the practical action and important mean on accelerating the construction of intelligent mines in China. In order to explore the layout method of intelligent dry separation system, The basic principle, key technology and main advantages of intelligent dry separation technology are introduced in detail, Two layout methods of underground intelligent dry separation system were put forward and introduced in detail by the engineering design case, which include the layout method of transfer point at the end of the main roadway and the layout method of the middle part of the main roadway. On this basis, The upgrading method of ground washing system is put forward In view of the problems faced by many coal mines, such as high labor intensity and low work efficiency of manual separation, which further expand the applicability of the intelligent dry separation system. Through the systematic research on the layout method of intelligent dry separation system, the design system of intelligent dry separation system is improved, which lays a foundation for the popularization and application of intelligent dry separation technology and the construction of intelligent mine.

For coal bunker position detection and distribution warehouse vehicle operation control of practical problems, to design a set of a continuous detection of coal bunker coal precision automatic control system for the coal, the mathematical model is established for detecting mobile positioning process, the position information in relation to the distribution warehouse automation control car, can through the accessory installation of radar level meter charging position signal real-time adjust the car speed, the control process and positioning data together, in addition to the storehouse car positioning error and position error of the indicator problems are analyzed and processing, improve the system accuracy. The field operation of Zhaozhuang Coal preparation plant shows that the system can realize the coordination between the warehouse position monitoring and the automatic control of the warehouse trolley. The automatic operation and precise coal dropping of the trolley are good, and the position detection is accurate. Meanwhile, the number of sensors is reduced, the maintenance cost is reduced, and the manpower and material resources are saved.

Aiming at the problem of imperfect monitoring function and low intelligence of coal transportation process in large coal storage silos, an intelligent monitoring system for coal transportation of large coal storage silos is designed, including data acquisition, robot inspection, real-time prediction, and trend prediction, fault identification, alarm management, historical playback, system management and other modules. Convolutional neural network and artificial neural network are introduced to model the equipment state, and a single indicator dimension and residual index of the equipment are proposed to judge the abnormal state of the equipment. The real-time accurate prediction and abnormal judgment of the equipment state are realized. The intelligent monitoring transformation of the Sanhe Power Plant’s coal storage silos, coal crushers, coal feeders, belts and other equipment are completed. The system improved the level of automated supervision and control, minimized operating personnel, and promoted the company’s intelligent operation. Moreover operation and maintenance costs are reduced, the production efficiency is improved.

based on a height-increasing and capacity-expansive dumping site project, rock mass physical and mechanical parameters was determined through on-site exploration. This thesis analyzes the displacement of dumping site, earth stress, plastic strain and judges the failure model of dumping landslide with the help of finite element. The height of slope dumping site and the slope angle sensitivity analysis are then confirmed based on the previous analysis. This author finally puts forward the operational scheme that dumping slope height is no more than 725 m and the slope toe is11° , so as to achieve the slope stability risk control.

Nanguan Coal Mine West Wing track Lane, West Wing belt lane and West Wing return air roadway are typical large deformation and difficult to maintain roadway under dynamic pressure. In order to ensure the safety production of coal mine, roadway excavation is in a state of frequent repair, which requires a lot of manpower and material resources for repair. In order to solve the support problems of three main roadways in Nanguan coal mine, based on the analysis of surrounding rock conditions, original rock stress and deformation characteristics of original support, a composite support scheme based on concrete-filled steel tube support is proposed. Field comparative test is carried out in the mining affected area by 3209 working face. The test results show that, compared with other reinforcement methods, the deformation of surrounding rock in the support section of concrete-filled steel tube support has been effectively controlled, and the designed support scheme of concrete-filled steel tube support is suitable for dynamic pressure roadway support in Nanguan coal mine.

The roof of roadway in Guqiao coal mine contained multiple layers of hard key strata, which transferred remote mining induced stress to make the deformation and failure control of the roadway difficult. When hydraulic fracturing technology was used to cut off those roof with multiple layers of key strata to prevent the stress concentration, it was required to fracture the hard key strata accurately and controllably, so as to ensure the effectiveness and safety of the construction. To check the implementability of controllable fracturing, the professional hydraulic fracturing system for rock and coal were employed to carry out tunnel protection filed experiment based on stress transfer through roof cutting. The experimental results showed that the real-time water pressure monitored near the borehole clearly indicate the hydraulic fractures propagation in different rock layers, and can be used as a reference for safety and effectiveness in the construction process. The roof could be effectively cut off layer by layer basing on real-time signal feedback of water pressure and precise fracturing with targeted point borehole sealing. After experimental construction, the displacements of roof and floor as well as side wall were less than 230 millimeters according to the monitored data. The mining induced stress were effectively transferred away and the deformation of the experimental tunnels were effectively controlled. This experiment provided an engineering example of tunnel protection basing on accuracy fracturing roof with multi-layers key strata, and may be referable for those mines with similar tunnel problems.

With the development of coal mining in Yima mining area, the mining depth continues to extend downward, and coal mining activities in areas with complex structures are inevitable. In order to improve production efficiency, large-scale equipment is gradually being adopted by coal mines. At the same time, the cross-sectional area of the roadway is also expanding to meet the needs of the use of large equipment and ventilation. The large cross-section roadway reduces the stability of the surrounding rock and brings another huge challenge to the support of the roadway. The roadway of 21170 mining face in Changcun Coal Mine is a typical large-section supporting roadway with serious deformation and heavy repair work, which has seriously affected the safe and efficient production of the working face. This article is based on the engineering geological conditions of roadway in 21170 working face of Yima Changcun Mine , Using on-site testing, numerical simulation, theoretical analysis and on-site testing methods to analyze the destruction characteristics of large-section support roadway, study the deformation and ring-breaking characteristics and support theory of large-section support roadway, large-section support Factors inducing deformation and failure of roof coal roadway, finally, the support technology of large section supporting roof coal roadway was determined and the expansion plan of 21170 working face roadway was determined.

In order to solve the problem of support difficulty caused by the high concentrated stress and dynamic pressure produced by the goaf of lateral working face in pangpangta coal mine, the optimization design of support materials, methods and support parameters was carried out, so as to reduce the overall surface deformation of roadway and ensure the safety and efficient mining of mining face. According to the actual conditions of mining roadway in 5-107 working face, the high-strength square arch bolt supporting plate with 150 × 150 × 10 mm and the high-strength square arch anchor cable supporting plate with the size of 300 × 300 × 16 mm are developed. The coupling support technology of timely high preload, strong bolt anchor cable, strong protection surface component and strong side support is proposed. The supporting parameters of 5-1071 and 5-1072 roadway are optimized, The analysis results of mine pressure monitoring data show that the roadway deformation after optimization design is within the controllable range.

In order to solve the problem of gas overshoot in the working face during the mining of the upper protective layer of a coal mine in northwest China, the directional drilling technique of gas extraction with downhole pressure relief was put forward. Introduces the selection of equipment and tools, the design method of drilling hole and the control of drilling track, and studies six key technologies of directional drilling construction, such as large angle hole opening, stable grouting solid pipe, mixed drilling, formation discrimination, rapid revolving through abnormal area and reserved branch point. The engineering test results show that the technology has advantages such as high success rate of hole opening, fast penetration through the hole area of broken rock, accurate formation identification, high drilling efficiency, flexible trajectory adjustmssent and reducing construction blind area. The gas extraction concentration of directional drilling is 35.7% on average, which solves the problem of poor extraction effect of conventional drilling, improves the utilization ratio of free gas extraction from the coal seam under pressure relief, and provides technical support for the scientific conception of gas extraction, coal and gas joint extraction in pressure relief mining.

Abstract：The stope with thin bedrock in loose aquifer was prone to frame crushing and water discharge accidents, In order to ensure the safe mining of thin bedrock stope, based on the geological conditions of 1512 (3) stope in Gubei Coal Mine, Comprehensive theoretical analysis, mechanical experiment and industrial test, The laws of roof structure, core mechanical properties and stope pressure behavior before and after ground pre grouting reinforcement in weathered zone of thin bedrock stope were studied, In order to analyze the effect of grouting reinforcement. The results show that:The effective diffusion range of ground grouting in weathered zone was more than 15m, After grouting, the cementation, compactness, impermeability and stability of weathered rock were enhanced, The average shear strength of core was increased by 40.6%, The overall bearing capacity of the roof was significantly improved, Combined with the hydraulic support with high working resistance, the safe mining of working face was realized.

A photovoltaic base was built in an open-pit coal mine backfill area. Its booster station was located at the edge of the backfill area. There was a small kiln-pillar goaf under the eastern boundary of the booster station. During the operation of the booster station for 3 years, the backfill area had gradually subsided and tilted tower structures. Comprehensive geophysical surveys (ground geological radar, single-point seismic, and transient electromagnetic methods), drilling and drilling television surveys were conducted on the area to find out the backfill area status and the extent of deep goafs. Designed the overall reinforcement of the foundation by combining shallow grouting in the backfill area and deep grouting in the goaf.According to previous engineering practice, laboratory experiments, and field tests, it determined the slurry ratio and grouting parameters. After construction was completed, the geophysical comparison method before and after the treatment, the drilling core and fluid leakage observation method, the wave velocity test method, and the observation of surface settlement and deformation were used to analyze the treatment effect, and the grouting effect in the backfill area and the goaf area was good through inspection, which eliminated the hidden dangers of further subsidence of the booster station foundation and the sudden collapse of the goaf area, it provided a reference for similar projects.

The strong dynamic pressure on the shallow working face in the Shenfu mining area often causes coal wall slicing and support accidents. At present, the top slab is treated by drilling or blasting along the slot. However, pyrotechnic products have greater safety risks. This article is based on the analysis of the roof lithology of Yanghuupan Coal Mine and the reasons for the shallow overhang. It is proposed to use directional hydraulic fracturing technology to destroy the integrity of the roof. Combined with the monitoring curve of the water pressure recorder, the pump pressure is adjusted in time and the degree of rock cracking and expansion is judged. Transfer the high stress on the working surface support away from the roof. Analysis of mining practice and mine pressure monitoring data show that. After directional hydraulic fracturing is used to treat the roof of the working face. The mine pressure at the working end appears to be significantly eased. The proportion of high resistance areas is significantly reduced. The resistance of the stent in the range of 5000~7000kN was reduced from 36% to 29%. After the pressure is relieved, the load on the support is basically normally distributed. It can be seen that the directional hydraulic fracturing technology is an effective means to control the environment of strong dynamic pressure stress at shallow depth and has broad application prospects.

Taking the first section of the 21st floor of Junde Coal Mine as the background, the prevention and control of rock burst in the first section of the open-cut tunneling under the influence of coal pillar is studied by means of field survey, simulation analysis and vibration field-stress field monitoring. The results show that: (1) the concentrated stress of the upper coal pillar and the high stress formed by the lateral supporting pressure of the goaf of the coal pillar in this section are the main force sources of rock burst; (2) The calculation model of stress distribution in coal pillar affected area and lateral bearing pressure in goaf of coal pillar are established, which has an impact range of 138m and an impact risk of 52m; (3) According to the site conditions, formulate specific prevention and control plans for the early, middle and late stages of opening and cutting through tunneling, so as to realize the safety of opening and cutting through. The research results have a certain guiding significance for opening and cutting in similar situations.

Abstract: In order to ensure the safe and efficient mining and solve the gas problem in the upper corner of the working face, based on the research of the development law of the overlying rock fracture, this paper studies the reasonable layout of the high-level borehole in the goaf roof. Taking the 20102 comprehensive mining face of shennanao coal mine as the research background, it uses the similar simulation, theoretical analysis and field test methods to study comprehensively, and uses the similar model Based on the research of fracture evolution field and so on, the distribution and change law of overburden with the compaction area and fracture area in the mining process of the working face are determined. The research results show that in the time sequence, the overburden fracture undergoes transverse fracture development, longitudinal fracture development, fracture field expansion with the mining of the working face In the process of fracture recompaction, the fracture expansion area is the reasonable location of high-level borehole, which can effectively improve the efficiency of borehole extraction. Therefore, this paper aims to find the dynamic fracture expansion area in the process of mining. Based on the dynamic expansion area obtained from this study, the author, based on the actual situation in the field, arranges multiple high-level borehole for gas extraction, and then studies the borehole Through the analysis of the extraction parameters, it is shown that the reasonable arrangement of the high-level boreholes is within the range of 30-50m from the roof of the fracture zone, which can reasonably ensure the hole forming rate and the high-efficiency extraction efficiency. Through the analysis of the extraction data, it can be seen that the arrangement of the extraction boreholes in this layer can effectively reduce the gas concentration in the upper corner (up to about 0.4%), and can be maintained stably.

The average slope of the stoping position in 21015 coal mining face of Chen silou Coal Mine is 24o and the maximum is 30o. Due to geological constraints, in order to ensure the safe and efficient withdrawal of coal mining face equipment, it is necessary to use the downhill withdrawal method. On the basis of considering the actual conditions of the working face and the technology of withdrawal, the method of optimizing the ending technology, setting the winch of retaining frame, and adjusting the construction process method of the support withdrawal is adopted. It realizes the safe withdrawal of the equipment in the working face under the condition of the large slope, solves the problems in the withdrawal process, and provides a new method for the withdrawal of the equipment in the working face under the condition of downhill.

Based on the engineering geological conditions and the large surrounding rock deformation of Huangling No. 2 Mine, the theoretical analysis and field test method are used to analyze the evolution law of surrounding rock fissures of coal roadway nglunder the conditions of double-wing mining, and the partition deterioration index of surrounding rock of roadway is proposed. The partition deterioration feature and influencing factors of coal roadway group surrounding rock are studied, and the partition reinforcement time-sharing reinforcement technology of coal roadway group is formulated. The results show that the surrounding rock of the coal roadway group shows obvious partition deterioration feature, namely the three zones of fissure: the extreme development zone of shallow fracture, the middle micro-fracture zone and the deep original rock zone; the proposed three zones of support: shallow support zone (0m~2m), the central control area (2m~5m) and the deep bearing area (5m or more,especially 6m~8m) with the key parts in advance to strengthen and strengthen, to ensure the stability of the coal roadway group.

In order to establish a tunnel TBM (full-face tunnel boring machine) penetration rate prediction model, this paper is based on 100 sets of rock mechanics and TBM excavation parameters obtained through indoor tests and field records in the Pahang-Selangor tunnel in Malaysia. First, 17 TBM penetration rate (PR) prediction models were established by using statistical regression analysis, artificial neural network, machine learning and ensemble learning. Then, a new normalized multi-index model evaluation method is proposed. Each evaluation index of the model, in turn, to convert the orientation consistency, normalized, summation and ranking, and the normalization method and the existing ranking method are used to compare and analyze the performance of the 17 prediction models, the results show that: (1) The multi-algorithm fusion improves the prediction ability of artificial neural networks and classification and regression tree models, but slightly reduces the prediction ability of support vector regression models; (2) Classification and regression tree model and ensemble learning model based on classification and regression tree have the best prediction ability and are more suitable for PR prediction; (3) The proposed normalization method provides a quantitative way for multi-index comprehensive evaluation between different models, and overcomes the shortage of traditional ranking method that cannot accurately identified when the difference of model prediction ability is relatively small. The study results provide theoretical basic for reasonable evaluation of TBM roadway construction period and estimation of engineering cost.

Due to the poor mechanical properties of the surrounding rock of the roadway and the thinner section of the lining used in the initial support, the roadway under adverse geological conditions often deforms before the secondary support, which slows down the construction progress and affects the construction personnel. Personal safety. Based on the above problems, this paper simplified the initial support lining structure of the roadway under near surface conditions to a two-hinged arch. Using the principles of structural mechanics, the bending moment and axial force calculation formulas of the semicircular arch arch ring with the arch toe as the living hinge were derived. At the same time, with the air return shaft of No. 1 mine in Xinjiang Yili Coal Mine as the engineering background, Flac3D software is used to numerically simulate the initial support after the excavation of the roadway in Yili Coal Mine. The results show that the lining thickness and surrounding rock level have a great influence on the internal force distribution of the lining semicircular arch: when the lining thickness and surrounding rock strength level decrease, the bending moment and axial force at the semicircular arch foot will decrease simultaneously; semicircular arch bending The maximum value of the moment fluctuates most sharply when the thickness of the arch toe of the lining is 1-1.5 times the thickness of the vault, and it stabilizes after the thickness of the arch of the lining increases further. When the thickness of the lining is insufficient and the strength of the surrounding rock is low, the elastic resistance of the surrounding rock has a greater impact on the axial force of the semicircular arch arch foot. Research shows that the living hinge calculation method is more suitable for the internal force calculation under this mechanical environment.

Influenced by the factors of early technology, economy and mine field division, many destruction areas of small coal mine are distributed in the upper coal seam of merger and reorganization mine. In order to reduce the waste of coal resources and geological disasters induced by the residual goaf, the re-mining of residual coal has important practical significance. In this paper, Hanzui coal mine #32101 working face thick seam fully mechanized caving mining as the engineering background, the similar simulation method is used to design the mining scheme, and the stability characteristics of surrounding rock and coal pillar in the upper layer goaf of #3 coal seam are inversed, the survey mark points are arranged and the simulation support is embedded, and the roof deformation law of fully mechanized top coal caving face passing through coal pillar and goaf is studied, the breaking rule of overlying rock in #32101 working face of Hanzui coal mine is revealed qualitatively. The results of this study provide experimental reference for the safe mining of the substituted working face in the mine field, and provide reference for the remining of the residual coal resources in the mine area under similar conditions.

In order to effectively predict the floor water inrush under the pressurized mining in the working face, based on No.15 coal seam in a coal mine as a study background. The failure depth of the floor is calculated by using the plastic theory and the empirical formula. Considering the influence of mining and occurrence factors, and based on the modified water inrush coefficient method, the formula of limit water inrush coefficient is put forward to determine the reasonable working face size and improve the accuracy of water inrush prediction.The water inrush of the floor is explored by site construction hydrological drilling, physical and mechanical properties of floor resisting stratum measured by the rock core，and comparison with theoretical calculation results. The possibility of water inrush from the floor of 15# coal seam is effectively predicted. The results show that: The main water-resisting layer of floor belongs to medium hard rock, which have water separation performance. The water content of the floor is weak, and there is no condition for water inrush from the bottom plate. The calculation results of ultimate water inrush coefficient show that there is no risk of water inrush in the complete section of the floor of the coal seam, but in the structure damaged fault section have. It is suggested to reduce the size of working face properly, find out the geological characteristics of the floor, and strengthen the water exploration and drainage in the weak areas such as the structure to prevent the water inrush risk.

The traditional mine hoist adopts the transmission structure composed of AC asynchronous motor and reducer and the TKD electronic control system to adjust the speed.This paper puts forward the permanent magnet rotor winding machine, its external rotor permanent magnet synchronous motor with integrated structure of the hoist drum with advanced frequency control system, has the transmission of simple structure, high efficiency and energy saving, start frequency is low, low speed running smoothly, and maintain the advantages of small volume, low noise, solves the problems existing in the traditional elevator long-term.In this paper, the principle analysis and simulation research are carried out on the variable frequency speed control system of the permanent magnet external rotor hoist (which is divided into vector control system and direct torque control system). The research results show that the variable frequency speed control system can realize the speed (or torque) closed-loop control of the permanent magnet external rotor hoist, achieving the effect of smooth operation.The torque and speed responses of vector control system are smooth.The torque and speed of DTC are faster, but the torque ripple is larger, so the optimization method is needed to eliminate the torque ripple.

This paper establishes a finite element model of the hollow structure of the thin-walled circular tube for the energy-absorbing components in the new spiral anti-impact device. The simulation results of the crushing performance of the hollowed-out thin-walled tube are verified by experiments. According to the model parameters verified by the experiment, the influence of the number and length of the vertical bars of the thin-walled circular tube structure on the axial static load crushing buckling deformation, the initial peak force, the displacement at the elastic stage, the average supporting force, and the suction of the thin-walled circular tube vertical bar structure are studied. The influence of the mean square deviation of energy and reaction force. According to the research rules and the actual working conditions of the anti-scouring column, the thin-walled vertical bar components are designed and tested, which provides the basis for the subsequent field shock pressure test. Studies have shown that the induced structure makes the deformation of the component more stable without changing the material, thickness and cross-sectional shape of the thin-walled tube; for the thin-walled tube vertical bar structure, as the number of vertical bars increases and the length of the vertical bars increases, the initial peak force, In the elastic stage, the displacement decreases, the energy absorption and the average support reaction force decrease, and the mean square error of the support reaction force decreases.

Aiming at the problems that it is difficult to obtain a large amount of coal mill fault data from the actual operating data of thermal power plants and the precise mathematical model of coal mill is difficult to obtain, which affects the formulation of its fault diagnosis strategy, this paper proposes a deep learning based on simplified mechanism model The fault diagnosis algorithm is used to effectively detect the operating status of the coal mill. Based on the mechanism model of the coal mill system, a large amount of fault data has been obtained through analysis and simulation of different fault types. And through the improved stacked auto-encoder (ISAE) to combine the simulated fault data with the deep learning algorithm to establish a deep learning fault diagnosis strategy, ISAE extracts the essential characteristics of the fault data layer by layer in an unsupervised way, with good learning and The ability to identify fault characteristics. The simulation results also show that the proposed ISAE can well detect the faults of the coal mill, the fault diagnosis accuracy rate is as high as 98.46%, and the early warning can be issued. Key words: Coal mill; Mechanism model; Deep learning; Fault diagnosis; Improved stacked auto-encoder

The equivalent permeability of the 3D fractured porous media is predicted based on fracture geometrical parameters of 3D model, the matrix permeability and permeability of 2D cut plane. 3D models of fractured porous media with different fracture characteristics were established, and the equivalent permeability of 2D/3D model were calculated. The results show that the equivalent permeability of the 2D cut plane is much smaller than the 3D equivalent permeability. The effects of fracture geometric parameters and matrix permeability coefficients on the equivalent permeability of the 3D model were quantified. Through regression analysis, a 3D equivalent permeability prediction expression based on 3D rock mass fracture length, density, matrix permeability and 2D equivalent permeability is obtained. This study provides the possibility to use the surface matrix-fracture characteristics to predict the permeability of 3D fractured porous media.

o explore soft coal seam gas extraction in the process of drilling damage, the space-time characteristics of borehole specimen under uniaxial compression test, and measurement by digital speckle correlation method (DSCM) observation of crack initiation, extension, and through the whole process of temporal and spatial evolution characteristics, through the deformation feature point extraction, analysis of the crack tip space, time and regularity of crack.The results show that the upper (lower) end of the borehole and the left and right end of the far field all have tensile cracks, the left and right sides of the borehole have shear cracks, and the rest of the cracks are affected by both tensile stress and shear stress.The failure process of the sample can be divided into five stages according to the spatial and temporal evolution characteristics of the fracture. The macroscopic main crack is formed by the penetration connection between the left and right cracks around the hole and the left and right cracks in the far field.The spatial and temporal characteristics of the failure process of samples containing boreholes are closely related to the longitudinal and circumferential fractures that are prone to occur in the pressurized area of boreholes, which reveals the nature of the separation and complex fractures of boreholes and provides some reference for the study of the crack growth law around boreholes.

The growth of flocs in flocculation process has a dynamic demand for hydraulic conditions. According to the theory of self-conservative coagulation kinetics, the design method of gradual change grid flocculation device is proposed, and a gradual change grid flocculation device is designed and processed with 300 S-1 as the initial velocity gradient. Under the optimized reagent condition, the experiments of flocculation and sedimentation of slime water in the designed device were carried out at the feed flowrate of 1.65, 2.28, 2.91 and 3.54 L/min. The results show that the floc size and the turbidity of supernatant are the best at 2.28 L / min, and the flow rate is close to the design value of 2.4 L/min, which shows that the design method is reasonable and reliable. Compared with the straight pipe flocculation and measuring cylinder turnover method flocculation sedimentation experiments, the turbidity of supernatant of slime water can be reduced by 12 NTU after flocculation sedimentation by gradual grid flocculation device, which indicates that the gradually reduced hydraulic velocity gradient in the device meets the requirements of flocculation kinetics and has advantages.

Considering the problem that the long distance and large-capacity belt conveyor, the force of the belt conveyor is too large, and the tensioning stroke is too large, which in turn causes the long frame of the vehicle-type tensioning device and the height of the tensioning tower. To meet the needs of construction requirements, by designing a multi-layer belt-wound tensioning trolley and double-rate moving pulley tower mechanism system to shorten the tensioning stroke, the length of the tensioning frame is reduced by half and the height of the tensioning tower is reduced by half. To meet the construction needs of narrow sites, strong adaptability, high degree of automation, no additional maintenance, considerable economic benefits, provides an important reference for the design of long distance belt conveyor tensioning system.

Abstract: Aiming at the problem that the front four-bar caving coal transition support is prone to uneven load on the front and rear columns and the caving coal transition support is likely to cause fatigue instability and failure of the main bearing structure under the impact load. Taking the top beam and base of the main structural parts of the anti-four-link caving coal transition support as the research object, the three-dimensional model of the top beam and base was established using SolidWorks, and the fatigue life analysis of the components was performed using the ANSYS Workbench finite element software. By analyzing the life cloud diagram, damage cloud diagram and fatigue sensitivity characteristic curve of the top beam and base, the maximum cumulative fatigue damage of the top beam and base and the parts prone to fatigue failure are obtained. The design research results show that the designed top beam and base have a small amount of deformation under load, and the maximum fatigue cumulative damage ratio of the top beam and base is less than 1, which satisfies the structural design life of each part of the transition bracket is less than the usable life.

Development of hydraulic punch while drilling, solves the problem that the hydraulic punch is required to insert after the drilling hole is finished in hydraulic punching construction in underground coal mine .Good results have been obtained in the drilling of the upward penetration layer hole. But in a near horizontal or lower oblique hole, Drilling slag is difficult to drain from hole with drilling fluid due to the gravity effect of drilling slag, which cause hole collapse accidents. In this paper, hydromechanical analysis is carried out on hydraulic punching construction process, and the loss the hole, the pressure of puncher hydraulic reversing valve and the flow rate of driling fluid needed was calculated. By adding water jets at the bottom, Increase the flow quantity of punching and the upstream flow rate of drilling fluid, So as to solve the problem of slag discharge difficulty. According to the improved hydraulic parameters, the reset spring of the punch was redesigned. The filed test was carried out which the improved hydraulic punch was used, tests show that the direction-change valve of the improved hydraulic punch works stably.Drilling slag can be discharged out of the hole in the near horizontal oblique borehole,which meets the requirement of hydraulic punching construction in under inclined borehole in coal seam.

Based on the status quo of dynamic sampling inspection of safety production standardization management system of six coal mines in the third quarter of 2020, the problems existing in the operation of the concept target and safety commitment of mine manager, organization, safety production responsibility system and safety management system, quality of employees and continuous improvement of four specialties and mechanized intelligent chemical minging face in the coal mine safety production standardization management system were analyzed.According to the PDCA cycle logic, measures such as strengthening publicity and implementation, strengthening spot test, compiling post standard operation process and job list, refining the division of responsibilities, improving paperless training system, realizing the linkage between intelligent chemical work and standardization, and improving the early warning of unsafe behaviors, are adopted to improve the standardized management system of mine safety production At the same time, it has a certain guiding significance for the realization of mine standardization dynamic standard.

Coal occupies an important position in China's energy structure and plays an important role in economic development. In order to analyze the trend of coal supply and demand in China during the "14th Five-Year Plan" period, combining the characteristics of small samples of coal supply and demand data, and using the relevance vector machine (RVM) algorithm, a coal supply and demand prediction model based on RVM was constructed. The coal supply and demand during the 14th Five-Year Plan period has been forecasted. The research results show that during the "14th Five-Year Plan" period, China's coal production and consumption are still steadily increasing. Coal mine safety production is still the main issue during the "14th Five-Year Plan" period. And relevant suggestions are put forward from the perspectives of government supervision, enterprise risk control and coal mine intelligent construction.