Abstract:Taking No.13208 haulage roadway driven in the isolated coal pillar of Maodi Coal Mine as the research object,the high stress redistribution and surrounding rock deformationand failure evolution characteristics induced by roadway driving disturbance in isolated coal pillar were analyzed,and the combined supporting parameters were optimized.Theoretical analysis was conducted on the lateral stress distribution of coal pillars and the characteristics of the limit equilibrium zone,proposing reasonable locations for roadway layout.Simulation analysis was performed on the stress distribution and deformation of surrounding rocks under different coal pillar widths.A combined supporting technology of bolt-mesh-anchor and U-steel shed was proposed,and reasonable supporting reinforcement parame-ters were determined.The"shallow-deep"grouting reinforcement method was proposed to enhance the self-bearing capacity of frag-mented coal and rock masses,and the grouting reinforcement scheme was determined.The on-site implementation results indicate that the optimized supporting scheme has reduced the deformation of surrounding rock,improved the stability of the gob-side roadway within the coal pillar,and achieved good barrier effects.The research provides technical support for the layout of high stress roadways within i-solated coal pillars and the strengthening control of surrounding rock under similar conditions.

Abstract:In light of the relevant policies,industry norms,and technical standards that have been introduced in the current evaluation system for coal mine intelligent construction indicators,Hongshan Coal Mine in Xinjiang was taken as the research object.Based on the principles of scientificity,systematicness,hierarchy,conciseness,operability,and expansibility,a"631"indicator evaluation system for the intelligent construction of underground coal mines was established.The entropy method was employed to analyze and calculate the weights of various indicators.Additionally,SPSSAU software was utilized to verify the rationality of indicator system through AHP meth-od,aiming to achieve the standardization,normalization,and data-driven evaluation and acceptance of intelligent construction in under-ground coal mines.

Abstract:As an important component of thermal power generation and nuclear power generation processes,the steam turbine plays a crucial role in converting steam heat energy into mechanical energy.It transfers rotational torque to the generator through a coupling,which in turn generates electrical energy based on the principle of electromagnetic induction.Given the importance of steam turbine,its protection system must ensure that it does not malfunction,let alone fail to operate,in order to maintain the stability of electric power and heat supply,as well as the safe operation of important equipment.

Abstract:Drilling cross-layer boreholes to extract pressure relief gas is crucial for enhancing the effectiveness of regional outburst pre-vention.Tucheng Mine is a typical coal mine with coal and gas outbursts occurring in multiple coal seam group.The protective layer is implemented as a regional measure.The simultaneous extraction of the current coal seam and pre-drainage of adjacent layers can pre-vent gas accumulation in the upper corner of working face and in goaf.Based on the geological and mining conditions of Tucheng Mine,a control equation for gas migration in coal seam group under the influence of stress field was established.Using the COMSOL mul-tiphysics coupling software,a comparative study and analysis were conducted on the effective radius of cross-layer borehole gas extrac-tion and pressure relief under different borehole arrangements in No.5 coal seam of Tucheng Mine.The key factors affecting the effective radius of cross-layer borehole gas extraction and pressure relief were identified and verified using measured data.The research can pro-vide theoretical guidance and technical support for the management of gas safety in similar mines.

Abstract:Using data from drilling,geophysical exploration,pumping tests,sampling tests,and long-term observation of water levels in 49 limestone hydrogeological boreholes in the northern wing of Guqiao Coal Mine,a detailed investigation into the lithological composi-tion and thickness of limestone in north wing No.1 coal floor,as well as the water levels of the limestone groundwater was conducted.A comprehensive analysis was conducted on the hydraulic connection between limestone and groundwater,and it was concluded that there is a hydraulic connection between the C3Ⅰ group limestone aquifer and the C3Ⅱ group limestone aquifer,a weak hydraulic connection between the C3Ⅱ group limestone aquifer and the C3Ⅲ group limestone aquifer,and a hydraulic connection between the C3Ⅲ group limestone aquifer and the Ordovician limestone aquifer.This provides reliable geological basis for ground area management,drainage and pressure reduction,and other water prevention and control plans.

Abstract:During coal mining,a large amount of dust is generated,posing health hazards to workers and posing safety risks such as ex-plosion hazards due to the presence of coal dust.Current dust prevention and control measures mainly include ventilation dust suppres-sion,equipment dust removal,coal seam water injection,and spray dust suppression.Based on the actual conditions of Hongqingliang Coal Mine,an intelligent dust suppression system that covers transfer points,tunnels,and mining faces was established.Through real-time sensing and intelligent analysis,the system has achieved rapid response and precise treatment of dust sources and effectively re-duced dust concentration in key dust-generating areas.This has improved the underground working environment and ensured the occu-pational health of employees.

Abstract:To address the challenges of poor adaptability of single supporting schemes for underlying roadways,significant deformation of surrounding rock,and instability of stabilized roadways caused by crossing roadway mining in extremely close coal seam mining,research was conducted using the east wing track roadway at-750 m level in Xuzhuang Coal Mine as the engineering background.Through nu-merical analysis,it is found that the initial influence range of lateral abutment pressure on both sides of the goaf was 36 meters,and the working face tended to stabilize after advancing 25 meters.Based on this,a targeted composite reinforcement scheme for roadway was proposed,utilizing full section high strength prestressed anchor bolts(cables)combined with metal mesh,ladder beams,and floor beam anchor bolts for composite reinforcement and supporting technology,to ensure the overall stability of surrounding rock.Field applications have shown that this technology effectively controls the deformation of surrounding rocks in deep crossing mining roadways,providing a theoretical basis and practical reference for the supporting of floor crossing mining roadways under complex geological and mining stress conditions in the deep.

Abstract:To enhance the recovery rate of coal resources and fully promote the application of small coal pillar mining technology,the No.2307 working face of a certain mine was taken as the research object.Focusing on the issue of reasonable dimensions for small coal pillars,a combination of theoretical calculations and numerical simulations was employed to analyze the characteristics of surrounding rock stress and displacement changes when the coal pillar dimensions were set at 5,6,7,8,9,and 10 meters.Research indicates that when the width of coal pillars is set between 7 and 10 meters,the pillars exhibit good load-bearing capacity,and the overall stability of roadway is high.Taking into account both safety production and economic costs,the optimal width for small coal pillars is determined to be 7 meters.Application practice has shown that coal pillars of this width can effectively ensure the supporting effect of roadway,reduce the frequency and intensity of roof pressure,maintain the surrounding rock in a favorable stress environment,and achieve safe mining of working face.

Abstract:Rock burst is prone to occur during high-speed or non-uniform speed mining in mining area.To reasonably control the min-ing speed of Yuangou Coal Mine in Shaanxi Province,taking the No.1012007 working face of mine as the research background,the o-verall correlation between microseismicity and the mining process during the working face extraction,as well as the relationship between fault zones and mining speed,were studied through numerical statistics and theoretical analysis.The numerical fitting method was em-ployed to optimize the extraction speed and determine the extraction speed for different impact hazard zones on working face.The re-search results indicate that:①the correlation between the mining speed and microseismicity is high on the No.1012007 working face,and the mining speed is the main factor affecting rockburst during the mining period on working face;②as the mining speed on working face increases,the nonlinear trend of daily microseismic frequency and energy intensifies.When the mining speed is at 5.6 m/d,the risk of rockburst on working face is relatively low;③based on the clear understanding of the frequency of microseismic events and their energy variation with the mining speed,the mining speed of No.1012007 working face was optimized.It was determined that the maximum advan-cing speed in areas with high rockburst risk is 4.8 m/d,in areas with medium rockburst risk is 6.4 m/d,and in areas with low rockburst risk is 8.8 m/d.The research results can provide a certain reference for the design of similar mining face extraction speeds.

Abstract:Geopolymer is a low-carbon and low-cost aluminosilicate cementitious material,and its early-age mechanical properties de-termine the effectiveness and feasibility of its engineering applications.Through uniaxial compression tests,the effects of different alkali activator content,alkali activator modulus,and water-binder ratio on the early-age uniaxial compressive strength of fly ash-slag geopolymer paste specimens were investigated.The experimental results indicate that when the dosage of alkali activator increases from 10％to 20％,the compressive strength at various ages continues to increase,with the order being J20>J15>J10.The increase in dosage promotes gel densification by enhancing alkalinity,thereby improving the mechanical properties of the material.When the modulus of the alkali activator increases from 1.0 to 1.4,the compressive strength at various ages decreases,with the order being M1.0>M1.2>M1.4.A low modulus promotes gel formation,while a high modulus inhibits reaction activity.When the water-to-binder ratio increases from 0.43 to 0.45,the compressive strength at various ages decreases,with the WB0.43 group having the highest strength.A lower water-to-binder ratio helps improve densification and gel formation efficiency.The research results can provide theoretical basis and experimen-tal reference for the early-age mechanical property regulation and engineering application of fly ash-slag geopolymers.

Abstract:When the well construction project of Xiaojihan Coal Mine in Yuheng Coalfield,Ordos Basin,approached and initially uncov-ered the upper No.2 coal seam of the Jurassic system,rare coal seam water inrush occurred continuously.The commissioned mine was classified as a medium-sized mine with hydrogeological type where the coal seam aquifer is the main direct water-filling source.Research on this specific type of aquifer and its associated water hazards is limited.To reveal the hydrogeological characteristics of such special a-quatic media,based on a water inrush process induced by the recent exposure of No.2 coal seam in Xiaojihan Coal Mine,hydrodynamic a-nalysis and analytical calculation methods were employed to study the hydrogeological parameter characteristics of coal seam aquifer.The results indicate that the water inrush process can be simultaneously generalized into a non-steady flow filling model centered around the water inrush point with a fixed drawdown,and a non-steady flow water level funnel expansion model with an average water inrush volume as an approximate constant flow rate.The hydraulic conductivity of the No.2 coal seam aquifer was determined to be 0.49-0.90 m/d,and the elastic storage coefficient was 4.25×10-3-8.03×10-3.Compared with the single-borehole steady flow pumping test during the explo-ration stage,the obtained hydraulic conductivity of the coal seam is approximately 10 times that of the pumping test results.The under-ground water inrush reveals the coal seam aquifer on a more realistic production scale and with a larger inrush volume.The obtained hy-draulic conductivity matches the mine water filling conditions,making the results more reliable.The coal seam water inrush is mainly a non-steady hydrodynamic process that consumes the stored water in the coal seam.In this case,the elastic storage coefficient is more important than the specific inflow rate.The research findings have addressed the deficiencies in water storage parameters of coal seam aquifers,providing crucial theoretical and technical supporting for guiding water hazard prevention during mine production stages,as well as for studying the types of mine water inflow in special aquifers and the mechanisms of special water hazards in the Ordos Basin.

Abstract:Shaanxi Guojiahe Coal Industry Co.,Ltd.is located in the Huanglong Jurassic coalfield.It is a mine with complex hydrogeo-logical conditions and rock burst.The main mining target,the extra-thick No.3 coal seam,is buried deep,and roof bedding water disas-ters have occurred repeatedly during mining,posing a serious threat to the mine's safe production.Based on this,in response to the fre-quently occurring coupled disasters of roof water inrush from separation layers and strong mine pressure in fully-mechanized top-coal caving mining of extra-thick coal seams,physical simulation experiments,ground pressure monitoring,microseismic analysis,and dy-namic water level analysis were employed to study the linkage mechanism and disaster-causing laws of water inrush from separation lay-ers and strong ground pressure.The results indicate that after the fracturing and instability of the key water-resisting strata during the uphill mining stage in anticlinal area,confined water flows bidirectionally along the water-conducting fracture zones and the separation layer spaces,triggering periodic water inrush and support crushing;the fracture angle of the strata in the axial part of the syncline is close to 90°,and after water filling in the bedding separation,the load transfer mode of the overlying strata changes,leading to a sharp increase in support load.Before water inrush,the water level in the long-term observation hole decreases in a step-like manner,and the microseismic energy and frequency exhibit synchronous anomalies.The time-domain variation characteristics of the two are consistent,making them suitable as early warning indicators.The coupling effect of the ground stress field and seepage field induced by the mining of extra-thick coal seams forms a combined disaster mode of roof-bedding water inrush.The research results can provide theoretical and technical support for the prevention and control of bedding water inrush in mines with similar conditions in Huanglong coalfield.

Abstract:One of the key challenges in the development of deep coal-measure gas reservoirs lies in the complexity of permeability dy-namics under high temperature and high pressure conditions.To explore the influence of temperature and effective stress on the stress sensitivity of coal reservoirs,the overburden permeability experiments were conducted under different temperatures(30,50,70℃)and different confining pressures(5,10,15,20,25 MPa)with the No.3 coal seam in Yushe-Wuxiang block of Qinshui coalfield as the re-search object.The results show that the permeability of No.3 coal seam decreases exponentially with the increase of effective stress and exhibits obvious stage characteristics:when the effective stress is below 8 MPa,the permeability drops sharply(with the strongest stress sensitivity);thereafter,as the effective stress continues to increase,the permeability attenuation rate decreases significantly and the sen-sitivity weakens.With the increase of temperature,the permeability of No.3 coal seam shows a decreasing trend:when the effective stress is less than 15 MPa,the decrease in permeability follows the order of 70℃>50℃>30℃;when the effective stress exceeds 15 MPa,the decrease in permeability follows the order of 50℃>30℃>70℃as temperature increases,indicating that the controlling effect of effective stress is stronger than that of temperature.The damage rate of coal sample permeability exhibits a three-stage evolu-tion pattern of"rapid increase-decreasing growth rate-stabilization"with the increase in effective stress.As temperature increases(30℃→50℃→70℃),the permeability damage rate increases from 53.8％to 72.7％.Under the same effective stress,the permeability damage rate of coal samples shows a decreasing trend,but the increase laws of damage rate varies across different stress ranges:when the effective stress is below 15 MPa,the permeability damage rate follows the order of 70℃>50℃>30℃;when the effective stress is greater than 15 MPa,the permeability damage rate follows the order of 50℃>30℃>70℃.The dimensionless permeability of No.3 coal seam decreases exponentially as effective stress increases.When the effective stress is less than 15 MPa,the decrease in dimensionless permeability follows the order of 30℃>50℃>70℃;when the effective stress exceeds 15 MPa,the decrease follows the order of 70℃>50℃>30℃.This indicates that increasing temperaturecan inhibit its decrease,but the dominant role of effective stress is significant.

Abstract:Fault-type rock bursts occur frequently in China,among which rock bursts in triangular coal pillars under penetrating faults pose a greater danger,severely restricting the safe and efficient production of coal mines.Taking the No.506 working face of a certain mine as the research background,the evolution law of stress and energy in triangular coal pillars during the passage of working face through a penetrating fault was studied through numerical simulation,revealing the impact mechanism of triangular coal pillars under penetrating fault.Based on the stress distribution characteristics of triangular coal pillars,impact stress indicators were established,and the impact hazard zones and levels of triangular coal pillars were divided.Combining the energy accumulation characteristics of triangu-lar coal pillars,classified prevention and control measures combining large-diameter drilling,coal body blasting,and roof blasting were proposed.The energy accumulation pattern of triangular coal pillars indicates that when the width of the coal pillar ranges from 50-150 meters and 0-50 meters,additional roof and coal seam blasting pressure relief measures need to be taken.The effectiveness of these pressure relief measures has been verified on-site.

Abstract:In order to solve the problems of anchor breaking,floor heave,roof falling,steel belt deformation and two-side indentation in the mining process of a thick coal seam working face in a mine,based on the analysis of the geological and mechanical conditions of the working face,guided by the nonlinear large deformation mechanics design theory of surrounding rock,the constant resistance large de-formation anchor cable was used for advanced support.The results show that under the geological conditions where the roof and floor are mainly composed of sandy mudstone and sandstone,the deformation of surrounding rock caused by mining thick coal seam(5.1 m)is serious;the constant resistance device based on the large deformation theory of surrounding rock can solve the problem of low elongation of traditional anchor cable,and achieve the purpose of maintaining the stability of roadway by absorbing variable performance and inter-acting with surrounding rock;compared with the traditional support scheme,the displacement of the roof and floor of the roadway is rela-tively reduced by 67 mm,and the displacement of the two sides of the roadway is relatively reduced by 76 mm.The effect of constant re-sistance anchor cable support on controlling the deformation of surrounding rock in thick coal seam is obvious.

Abstract:As an indispensable part of mine safety production,underground transportation vehicles operate in a relatively complex envi-ronment,which poses higher requirements on the safety and stability of vehicles.Taking the No.110701 first mining face of Hongshan Coal Mine as the engineering background,a study was conducted on the applicability of explosion-proof diesel crawler transport vehi-cle.These vehicles are capable of completing slope climbing and material transportation under complex transportation conditions,which has promoted the upgrading of auxiliary transportation system in the mine and provided a guarantee for safe production in the mine.

Abstract:Addressing the severe deformation and maintenance challenges of roadways caused by repeated mining and intense dynamic pressure under the influence of hard roofs in close range coal seam group,a study on roof cutting and pressure relief technology was con-ducted based on the closely spaced coal seams of a certain mine.Through UDEC numerical simulation,the parameters of roof cutting height and angle were optimized,and the effects of roof cutting and pressure relief were comparatively analyzed.The research results in-dicate that a roof cutting angle of 15°and a roof cutting height of 19 m can significantly enhance the stability of surrounding rock in roadway.A reasonable roof cutting and pressure relief scheme was formulated,and the on-site application effect was good.The deforma-tion of roadway roof and floor,both sides,and coal pillar side was significantly reduced,and the stability of surrounding rock of roadway was effectively controlled.

Abstract:Addressing the issues of identifying remaining coal pillars and the stress transfer in mined-out areas of multiple coal seams,the coal pillars in the mined-out area of Lower1 coal seam in a mine in Xinjiang was taken as the engineering background.The FLAC3D numerical simulation method was utilized to analyze the plastic zone range and stress transfer of coal pillars with different widths in goaf of Lower1 coal seam,and identify the critical value of the width of remaining coal pillars.Based on the protective layer mining theory,the influence range of the remaining coal pillars was calculated,and a technical plan for monitoring and prevention of mining and excavation work faces under the influence area of the remaining coal pillars in goaf was formulated.The results indicate that the critical width of re-maining coal pillar in goaf of Lower1 coal seam is 22 m;the stress peak of the 24 m remaining coal pillar is the highest,reaching 48.8 MPa,which has the potential to induce rock burst;as the width of coal pillar increases,the stress peak gradually decreases.When the coal pillar width is 200 m,the stress distribution of coal pillar exhibits a plateau pattern;the influence range of remaining coal pillar in goaf of Lower1 coal seam in terms of strike and dip is 45 m and 20 m below and on both sides of coal pillar,respectively.The research results can provide references for the identification of remaining coal pillars in goaf of multiple coal seams,as well as for the prevention and control of rockburst in the affected areas of underlying coal seams passing through the remaining coal pillars.

Abstract:In order to further improve the recovery rate of coal resources in the fully-mechanized mining of ultra thick coal seams,the fully-mechanized caving face of No.6 coal seam of Bulian Gou Coal Mine was taken as the research object,by analyzing the top coal ca-ving ability through drilling observation and combining with the on-site coal caving effect,the optimized technical measures for top coal caving process parameters such as collaborative fine coal caving technology,initial mining staged coal caving,maximum coal caving in the end transition section,and final mining limited thickness coal caving were proposed and applied on-site.The application results show that the resource recovery rate of working face has increased by 5.6％,reducing resource waste and improving the economic benefits of mine.

Abstract:As one of the six major systems in coal mines,the coal mine transportation system is responsible for the transportation and lifting of personnel and materials in the mine.Due to objective reasons such as changes in mining levels and adjustments to production layouts,it is necessary to promptly optimize,adjust,or upgrade the main transportation and lifting systems.Based on the research back-ground of improving the production capacity of No.5 coal mine in Hami Energy Co.,Ltd.and upgrading the conveyor in the main haul-age roadway on the west wing at the+170 m level,there is an objective need to upgrade the DSJ80/40/2×75 conveyor to a DTL140/200/2×450 conveyor.After comparing multiple schemes and comprehensively considering factors such as investment cost,installation time,and operating cost,it was determined to move the drive unit backward to the junction of the main haulage roadway and the main and auxiliary combined roadway in the west wing.The large components were constructed using an integrated secondary grouting process.The successful application of permanent magnet rollers in belt conveyors ensured the operation capacity of coal and gangue,while meeting basic requirements such as pedestrian access and maintenance standards in the roadway.This laid the foundation for the intelligent transportation system in the mine.