Inordertoresearch the problemofthe roadway layout onthecondition of external-misaligned stagger arrangement,according to the research status of domestic gob-side entry driving, the top coal stress division of 302 working face was divided by theoretical calculation. Numerical simulation analysis compares the stress field and plastic zone distribution between the condition of direct excavation and goaf backfilling. The stress field and plastic zone distribution of direct excavation face, large deformation setting of working face and filling simulation of goaf are compared and analyzed by Flac3D numerical simulation software.The result shows that the calculation error of working face in upper section of direct excavation is large.The calculation error of excavation face is reduced after large deformation treatment, and the filling simulation of goaf is the most accurate because it accords with the actual conditions. Finally, considering the theoretical calculation and the numerical simulation results of the filling process in the goaf, the horizontal offset of the lower section along the bottom roadway is determined to be 3m. Joint space support relationship between adjacent roadways is proposed by combining the spatial positional relationship of the wrong layer. The experimental results were verified by Flac3D numerical simulation software. The final result is that the roadway layout and support scheme is beneficial to reduce the size of the coal pillars, improve the resource recovery rate, and at the same time, it can control the adjacent roadway between the sections.

Abstract: In order to avoid large area roof weighting and reduce the cost for deep gob-side entry retaining with hard roof, a method for gob-side entry retaining by short-hole blasting and narrow backfill was proposed. The FLAC3D software is used to simulate three kinds of gob-side entry retaining schemes under the width of the backfill. The width of the backfill is determined by comparing the deformation of surrounding rocks. Through theoretical calculation and engineering practice, the blasting parameters of short-hole are determined. The monitoring data of mine pressure show that the method of short-hole blasting and narrow backfill can effectively cut off the side roof of the mining area, so that the remaining lanes can meet the requirements of reuse.

Mine water inrush is a common mine disaster which is sudden and intense. When a mine flood occurs, In order to reduce material losses and casualties caused by disasters, a mine flood escape route planning method based on bidirectional A* algorithm was proposed. On the basis of fully considering the factors affecting the escape of roadway, a reasonable evaluation function was selected, and the escape route is planned by bidirectional A* algorithm to achieve optimal design. Combined with the Wangjialing coal mine example and comparing the planning result of the bidirectional A* algorithm with the planning result of the traditional A* algorithm, the simulation results show that the escape route of the algorithm is less than the traditional A* algorithm node, and the path is better, so to a certain extent It can improve the escape rate of employees and has certain application value.

Abstract: Because of the particularity and complexity of the operating environment of the low-voltage power grid in coal mine, the speed and accuracy of fault line selection by using the zero-sequence current of single-phase grounding are greatly affected. Therefore, on the basis of in-depth study of the characteristics of single-phase grounding in Small Current Neutral Grounding System, this paper puts forward the idea of combining two Small Current Neutral Grounding System for fault line selection, that is, normal operation of Isolated Neutral System when single-phase grounding, the system will operate in state of Neutral Point Grounding via High-resistance for fault line selection, after completing the fault line selection, it will return to the original state of Isolated Neutral System. A practical circuit integrating two Small Current Neutral Grounding System is given. Under the premise that the zero-sequence current of high-probability fault line is the maximum, this method can effectively improve the accuracy of fault line selection and the sensitivity of protective action by utilizing the difference between the fault and non-fault line feature which is significantly increased.

Due to the low bearing capacity of surrounding rock in coal mining roadway in western China, it is difficult to control the deformation of surrounding rock effectively by general bolting and spraying support. The common roadway sinking, bottom drum and film state phenomenon, the roadway repair rate remains high. The reason for the analysis is mainly the bolt isolation effect caused by the failure of the bolt to pass through the loose ring of the roadway and the stress concentration of the surrounding rock near the anchor. For this reason, based on the loose rock circle theory of the surrounding rock, the thickness of the loose ring of the roadway is calculated. According to the calculation of the bolt length; based on the key part support principle, the length, position and row spacing of the anchor cable are determined; the length and spacing of the counter-arch anchor are determined according to the slip line theory and plastic limit analysis method of the roadway floor. . In the construction of 113082 track mining roadway in No.1 Coal Mine of New Shanghai, the steel strip, anchor cable joint support and anti-bottom arch support scheme were designed. Numerical simulation shows that the scheme effectively improves the surrounding rock stress state and better control. The surrounding rock deformation of the roadway; after the implementation of the site, the continuous deformation of the roadway was controlled to ensure the safe production of the coal mine.

Aiming at the complicated surrounding rock condition and roadway failure under the original supporting form in the lower 23 mining area of Juji Coal Mine, the ground stress and surrounding rock loosening zone of the lower 23 mining area are tested. The results show that the horizontal stress of the roadway is greater than the vertical stress, and the ground stress characteristics are of the horizontal stress field type, and the roadway surrounding rock loosening zone belongs to the roadway surrounding rock loosening zone. Yu Dasong moved around the soft rock roadway. According to the principle of continuous beam support, the large bolt combined with longitudinal and transverse steel band staggered combined support is adopted, and the support of the side is strengthened, the whole control of the surrounding rock of the roadway is realized, the deformation of the surrounding rock of the roadway is effectively prevented, and the better supporting effect is obtained, which provides certain technical reference for the roadway support under similar conditions.

Taking roadway layout in 18m residual coal pillar of Ohoblak coal mine as background. By means of field measurement, theoretical analysis and numerical simulation, the stress environment and deformation state of the residual coal pillar in the goaf are studied. The vertical stress distribution, deformation mechanism and plastic distribution state of the coal pillar under the condition of narrow coal pillar with different width are analyzed, and the narrow pillar width in the laneway in the residual coal pillar in the goaf is determined as 4.0m. On this basis, the control principle and technology of roadway surrounding rock in residual coal pillar are put forward, and industrial tests are carried out. The actual maintenance effect of the test roadway is good.

In order to solve the problem that the roadway in the 9102 working face of Heng sheng coal industry is affected by the overburden movement in Goaf, the tunnel deformation is rapid, the displacement quantity is large, and the ore pressure appears violently. Through the field surrounding rock deformation observation, drilling peep, Rayleigh wave detection and other means to the Heng Sheng Coal industry 9102 face Machine Lane monitoring. Through the field surrounding rock deformation observation, drilling peep, Rayleigh wave detection and other means to the Heng Sheng Coal industry 9102 face Machine Lane monitoring. Rayleigh wave detection roof indicates that the abnormal area of rock mass structure is distributed in 1m~1.5m and 2m~5m, the damage of roof drilling peep image is seriously damaged near 1.5m and 3m, the collapse hole appears at 4m, the roof off-layer instrument appears off layer in 2m~3m and 3m~5m. According to the monitoring results, the supporting parameters are optimized and tested, and the results show that: the deformation of the surrounding rock of 9102 Machine Lane is small, the displacement of the top bottom plate is 77mm when the measuring point is 140m, the displacement amount of the two pairs is 98mm, and the effect of roadway support is obvious.

The moving face of fully mechanized coal mining face is an important link in mine production connection. The selection of construction technology determines the construction progress and construction safety.In view of the moving problem of 50102 working face in haohaogou coal mine, according to the principle of system analysis, through finding the key link and grasping the key link, starting with the 2 aspects of the hydraulic support handling and handling equipment, the single channel double wing retracting process is studied and optimized, which improves the fully mechanized mining and moving speed, reaching the advanced level in China. Better economic and social benefits have been made.

The 4205 working face of Haoda Coal Mine is located in 4-2 coal seam. There is room-pillar goaf in overlying 3-2 coal seam. Influenced by coal pillars left over from overlying coal seam, the mining process of 4205 working face is prone to sudden and violent roof pressure, and the law of pressure is not obvious, and the support is frequently crushed. By means of field measurement and theoretical analysis, the main pressure causes of working face are analyzed. Combining with the theoretical criterion of pillar failure and instability in room-pillar goaf, it is concluded that the roof is prone to severe weighting near the edge of room-pillar goaf or blasting goaf, and the support is directly damaged. By shortening the inclination length of the working face, the improvement measures of the working face are put forward to reduce the cross-area range of the upper room-pillar goaf, thereby reducing the risk of large-scale roof collapse of the goaf, and good application results are obtained in the field, which provides the experience of efficient and safe mining for mines with similar conditions.

In order to prevent and control the rockburst problem of gob-side entry with 80 m section coal pillar in 1301 working face, the main influence factors were investigated, seismic wave CT was used to detected the static load of rockburst area for burst hazard assessment, and the prevention measures were formulated and applied. The results show that:(1) the rockburst load source of wide coal pillar was static load composed of the high gravity stress, strong tectonic stress and the lateral abutment pressure of goaf; (2) In-situ evaluation technology of seismic CT based on static load detection showed that the burst hazard indices of wide coal pillar were C=0.5-0.7 and had moderate degree burst hazard; (3) large-diameter borehole pre-relief technology was used to transfer concentrated stress and dissipate elastic strain energy of roadway side, full roadway section was designed to improve the anti-impact ability; reasonable advancing speed was determined to reduce mining disturbance, the comprehensive monitoring-early warning was determined the dynamic burst hazard area and pressure-relief measures. Field application shows good effect.

In order to improve the efficiency of gas extraction in Zhangji Coal Mine, in view of the characteristics of high in-situ stress and low permeability of the coal seam, similar tests and engineering applications were used to study the characteristics of fracture development, expansion and evolution in the process of hydraulic fracturing coal seam, and the mechanism of pressure relief and permeability enhancement in overburden strata. The fracturing technology combining "repetitive fracturing" with "first fracturing and then flushing" through drilling holes is put forward to increase coal seam permeability. According to the simulation results, the field engineering test is carried out by selecting reasonable fracturing parameters. The results show that the hydraulic fracturing technology can effectively improve the gas extraction quantity and shorten the time of meeting the standard.

Aim to reveal development characteristics of water flowing fracture during mining under extra thickness Luohe aquifer in mining thick coal seam in Tingnan coal mine, the law of development characteristics of water flowing fracture with different mining height. Results showed that measured value of water flowing fracture in NO.204 working face was 144.0m with mining height 6 meters, which was 140.2 m with mining height 7.5 meters in NO.206 working face, and 148.3 m with mining height 9.0 meters. The water flowing fracture developed near the bottom of Yijun aquifer, but not directly destroyed Luohe aquifer. The water flowing fracture did not increase linearly with the increase of mining height, but controlled by the location of key stratum in overburden. Measured results also verify that the discriminant method based on theory is correct and its applicability in Tingnan coal mine. The value of water inflow in NO.204, NO.205, NO.206 working faces also did not increase linearly with the increase of mining height also verified that the water flowing fracture did not directly destroyed Luohe aquifer. According to this research, the max mining height of working face could increase to 14 m theoretically and the coal recovery rate can be appropriately increased. The research results can provide reasonable design of mining height and roof water prevention for the mining of other panel in Tingnan coal mine.

In order to study the influence of mining sequence of upper and lower coal seams on the pressure behavior of interlayer coal strata in compound residual mining area, taking the compound residual mining area formed after mining the upper and lower coal seams of Xishan Coal Power Baijiazhuang Coal Mine by using the cutter pillar method and the long wall caving method respectively as the research object. The method of combining site survey, theoretical analysis and numerical simulation were used to research the influence of mining sequence on upper and lower coal seams on the stress distribution, movement and deformation, failure characteristics of abandoned coal and its surrounding rock in the middle part of the coal seams. Research results show that: 1) Compared with the mining sequence of “downward and upward”, when the mining sequence was "upward and downward", the degree of stress concentration in the middle coal seam and the surrounding rock are lower after the mined of the upper and lower coal seams, and the stress effect caused by double mining is smaller; 2) When the mining sequence is "upward and downward", the displacement deformation of coal and rock strata are smaller than that is "downward and upward" mining sequence; 3) When the mining sequence is "upward and downward", the rock mass below the cutter pillar isn’t damaged by plastic collapse and which means that the overall stability of the coal seam in the middle of the area is better. This paper provide support for the safe mining of abandoned coal in the middle of the compound residual mining area.

In order to study the coal bump mechanism in 13230 working face of Gengcun Coal Mine under the control of huge thick conglomerate and large thrust faults, field measurement and analysis were carried out on geological characteristics, microseismic spatio-temporal evolution, b-value and energy characteristics and surface subsidence variation characteristics during the period of excavation and mining. The results show that the high-level stress produced by thrust-slip movement of F16 and the high vertical stress produced by large area hanging of thick conglomerate provide the stress condition for coal bump. The distance between 13230 working face and F16 fault is far during the period of excavation and initial mining, so the slip movement of fault has little effect but the movement of huge thick conglomerate has great influence on it, and the increasing energy accumulation of coal and rock mass eventually leads to severe coal bump accident. With the 13230 working face gradually approaching to the fault, the influence of fault slip movement enhances, and the phenomenon of surface uplift is obvious, and the even energy accumulation of coal and rock mass eventually induces concentrated slighter coal bump behavior. The results provide a theoretical basis for the study of coal bump mechanism of 13230 working face under the influence of huge thick conglomerate and thrust fault.

In order to solve the problem that dynamic disasters are easily caused by repeated mining of very close coal seams, a comprehensive method of similarity simulation, numerical simulation and field application is adopted in this paper. The results show that when the roof and the goaf of the underlying working face are pushed to 85 m distance in the repeated mining process, the penetration area increases with the mining of the working face, resulting in irregular periodic weighting of the lower working face. The caving angle in front of the underlying working face decreases as a whole with the advancing of the working face, while the later caving angle increases, and the angle changes obviously when the working face advances to about 85 meters. Compared with the first mining, the stress concentration in the process of repeated mining is relatively mild and the influence range of pressure relief area is larger. But when the working face is pushed near the influence area of coal pillar in the first mining face, it is easy to cause the phenomenon of rapid stress growth and strong dynamic pressure. The preventive measures of strong dynamic pressure in working face under the condition of repeated mining of extremely close coal seam group with unified time-space-strength are put forward, which ensures the safety of working face.

In order to solve the problem of lack of theoretical support for the utilization of the hulking features of top-loading pressure relief rock in the deep Buried and medium-thick coal seam, a method for measuring the broken expand coefficient of different measuring points of the top-loading pressure relief rock based on 110 method is proposed. The evolution law of the broken expand coefficient of the top-loading pressure relief rock is excavated, and the hulking features of the the top-loading pressure relief rock are identified. The results show that with the advancement of the working face, the broken expand coefficient of each measuring point becomes smaller, and the stable value is between 1.356 and 1.385. The the top-loading pressure relief rock has the features of gradually decreasing the broken expand coefficient and advancement of the working face. The research results are of great significance for the utilization of the the hulking features of top-loading pressure relief rock in the large-depth and medium-thick coal seam.

For the reinforcement of surrounding rock of roadway with fully encapsulated cables, Anchorage and failure mechanisms with the two aspects are analyzed and studied in two stages: the axial additional stress of the surrounding rock mass and the shearing resistance of the weak surface such as joint in the end anchoring stage; The axial additional stress of the surrounding rock mass and the shear resistance of the joint weak surface during the fully encapsulated stage. The following conclusions can be drawn: 1. Pre-stressed full-length anchoring can transfer the shallow surrounding rock stress to the deep part by prestressing; 2. Pre-stressed fully encapsulated cables improves the targeting of support rigidity and resistance; The anchor has decoupled energy absorbing flexible support performance. The prestressed fully encapsulated cables is better than the anchor cable, and the support performance is greatly improved. The technology has been successfully applied in the Huainan mining area, and significant technical and economic benefits have been achieved.

The COMSOL numerical simulation software was used to establish a three-dimensional rectangular roadway borehole crossover model to study the circumferential stress distribution and displacement of the borehole under the influence of different ground stresses. The research shows that by analyzing the Mises stress distribution around the borehole under different ground stresses, the compressive stress on the left and right sides of the borehole is obtained, and the upper and lower sides are subjected to tensile stress, showing a "butterfly shape". Through numerical simulation and field test, it is shown that the borehole is affected by overburden rock stress and roadway stress redistribution, and it is easy to produce borehole damage within the range of 0~20m from the orifice, which is about twice the width of the roadway. By analyzing the stress distribution and displacement variation of the borehole under different earth stresses, the circumferential stress and displacement of the borehole exhibit a strong power exponential relationship with the increase of the bore depth.

Ensuring the stability of open pit slope is the front topic of its safety in production, and the stability analysis of working slope is the basis of effective control of slope stability. Combined with the geological conditions and present situation of the slope in Weijiamao opencast coal mine, through numerical simulation calculation and analysis, the failure mechanism and failure mode of the slope are analyzed from the most intuitive displacement characteristics of slope deformation, shear strain and plastic zone expansion. The conclusion shows that the slope slips along the bottom of the weak layer with circular arc along the bottom, and causes the failure of overlying silt and silt layer. The slope body is mainly excavated and unloaded and shear failure mechanism, macroscopical. The mode is shown as the creep and crack type traction landslide, which is the failure mode of the flat push which is cut by the arc of the rear edge of the bottom plate and the trailing edge of the bottom plate. According to this conclusion and in combination with the on-site fact, the comprehensive landslide control scheme of the "Real-time monitoring + dredging and drainage + stripping" is put forward to the slope stability control, the stability of the slope is improved, and the safe and stable production of the mine is guaranteed.

Air leakage in goaf easily leads to coal spontaneous combustion, gas accumulation and other disasters, threatening the safety of coal mine production. In order to study and master the distribution of air leakage flow field in goaf, taking 3308 working face of Liangbaoshi Coal Mine as the research object, a three-dimensional model of goaf was established, and the distribution function of resistance coefficient and porosity was constructed. The air leakage flow field in goaf was simulated by CFD software. The results show that air leakage exists objectively in the face of goaf, and the distribution of air leakage flow field has obvious regional characteristics in all directions; the main air leakage in the goaf occurs in the range of 0-10 m inclination of the working face, and the sealing work in this range should be strengthened to isolate the air leakage passage; the distribution trend of air leakage along the inclination of the working face obtained by numerical simulation is basically the result of field measurement. The agreement verifies the correctness of the numerical simulation. The above analysis provides a theoretical basis for reducing air leakage in goaf and preventing spontaneous combustion of residual coal in goaf.

Aiming at the serious cavitation problem of mine water hydraulic support safety valve, a CFD multi-phase flow model of valve chamber was established. The pressure and gas phase distribution characteristics of valve chamber flow field were studied. The influence of valve core structure parameters (valve outlet row number, valve outlet number, hole spacing, hole diameter) on the cavitation characteristics of important valve orifice overflow section was analyzed, and the structure parameters of valve chamber were optimized. The results show that the maximum volume fraction of vapor phase decreases by 19.4% when the spool is two rows of orifices, the number of orifices is 16, the diameter of orifices is 1.4 mm and the spacing of orifices is 8 mm, which can inhibit the formation of cavitation erosion.

Through the parameters such as device form and voltage were tested by distributed high-density resistivity method in the known goaf of a mine in Ordos, the electrical response characteristics of the profile curve, typical profile and stereo slice were analyzed. The optimized test parameters and identification features of goafs were analyzed systematically. The results showed that through the distributed high-density resistivity method was used to optimize the test, the corresponding curves, two-dimensional sections and three-dimensional slices were analyzed to form a feasible and effective detection.

Absrtact: In order to solve the problems of ecological fragility and scarcity of water resources in coal-rich areas of Western China, rational utilization and protection of water resources, artificial dam body is connected with safe coal pillar dam body, and mine water is purified, stored and utilized through closed goaf, thus forming a mine underground reservoir. The safety of artificial dam body is the precondition of normal operation of groundwater reservoir. The safety evaluation of dam body includes many indexes, criteria and levels. In order to objectively and accurately evaluate the safety of dam body, the weights of factors at different levels are calculated by analytic hierarchy process (AHP). The comparative judgment matrix is established and the consistency test is satisfied. The evaluation set is established to be fuzzy. Based on the theory and expert questionnaire, the membership degree of the evaluation factors is determined and the evaluation matrix is obtained, and the safety of the artificial dam body is evaluated comprehensively. Finally, the artificial dam body of Daliuta underground reservoir in Shendong mining area is evaluated by multi-level fuzzy comprehensive evaluation. The results show that the dam body is in a safe state.

Abstract:Multi-rope friction hoister exists the problems of imbalance wire rope tension and the ascending overload.The wire rope tension measured by the general sensor exists severe fluctuations and can not represent the actual tension and load effectively.A kind of particle damping vibration attenuation sensor is designed,which is loaded with steel beads in the cavity structure. When the sensor is pushed by the piston rod,the particle damping vibration is induced by the collision and friction between the steel balls and between the steel ball and the container wall. The impact load caused by the coupling vibration of the wire rope can be dissipated effectively and the noise in the tension signal of the wire rope can be filtered out.by the particle damping vibration.Compared with universal pressure sensor, this sensor can monitor the tension and lifting load of wire rope more accurately and effectively.

Lignite has wide size distribution, diverse composition, variable initial moisture content and complex drying characteristics. The effects of particle size, density，initial moisture content and temperature on the drying characteristics of lignite were investigated. The variation of moisture content of lignite with drying time was obtained. Based on the experimental data, the drying equation of lignite was established. The results show that lignite experiences two stages: fast drying and slow drying. The drying rate increases with the increase of particle density and temperature, and decreases with the increase of particle size and initial moisture content. The optimum drying kinetics model of lignite is Page model. Model constants have empirical relationships with particle size, density, initial moisture content and temperature. The equation can well predict the dynamic moisture content of lignite during drying process.

The dynamic performance and portability of mine intrinsically safe detection robot are the premise of whether it is suitable for mine disaster area. In view of the contradiction between enhancing power and reducing quality in the design of power system for mine intrinsically safe detection robot, Creatively put forward the use of distributed power + motor series force to provide power for intrinsically safe detection robot, establish the multi-objective optimization function of the power system design, the optimization goal of system is determined, the decision variables and constraints, and further obtained the mining safety of the motor and the reasonable value range of the battery. Through optimization, the weight of the robot was reduced to 10.8kg, 29% less than the original design. The test results show that the optimized walking speed and obstacle breaking ability of the robot are improved, and the performance parameters meet the design requirements, enhanced the safe detection robot dynamic performance and portability.

Roadheader is the key equipment of coal mining. The efficient and stable work of roadheader contribute to improve the efficiency of coal mining.Aimed at the problems of coal seam characteristics of complicated and changeable, boom-type roadheader cutting coal with drastic load disturbance change. Constant power speed control system for roadheader based on fuzzy self-adaption with MCU is proposed. Fuzzy adaptive algorithm is used to speed adjustion of horizontal oil cylinder line speed and SIMULINK software is designed to verify simulation. The results show that the control system designed can adjust the the swing speed of cantilever according to coal and rock characteristics,the working efficiency of the roadheader is improved.

In order to further explore the characteristics of the permanent magnet excitation device for steel wire rope nondestructive testing, a comprehensive analysis of the excitation device was carried out in order to improve the performance of the detector. The three-dimensional modeling and finite element simulation method are used to analyze the influence of the position of the permanent magnet in the permanent magnet excitation device and the excitation circuit on the excitation effect. The structure size of the excitation device for the excitation of the steel wire rope with a diameter of 36 mm is designed and used. The device excites the wire rope with a diameter of 16-36mm, and analyzes the excitation effect by equivalent magnetic circuit calculation and finite element simulation. The research results show that placing permanent magnets on both ends of the permanent magnet excitation device can form a uniform magnetization section in the middle of the excitation device, which is beneficial to the placement of the detecting components. The multi-circuit circumferentially distributed excitation magnetic circuit can make the steel wire magnetize more evenly and It is easier to magnetize the wire rope to saturation state; the permanent magnet excitation device has universal property.

Coal mining operation group is in the organization of coal mining enterprises small social network, this paper based on the research of social network theory and trust theory, proposed coal mine group network dimension (strength, asymmetric relationship) and structure dimensions (network density, network centricity, network scale, structural holes, condensing subgroup) through interpersonal trust influence the spread of the unsafe behavior in the network. Data were obtained through the questionnaire survey, the theoretical model was tested, and the conclusion was drawn that each dimension affected the diffusion of unsafe behaviors through mediating variables, and then the control measure of unsafe behaviors based on the group were proposed.