Advanced Materials Research Vols. 734-737

Abstract: According to the theory of gas flow in coal seams, and according to drainage standard and the other relevant laws and regulations, derived the calculating equation of efficient radium of drilling hole gas extracting in drill holes in coal seam and drill holes along seam. Efficient radium of drilling hole gas extracting was calculated, combining with field practice of coal seam named 1 in Xinji No. 2 coal mine, the comparison with efficient radium of drilling hole gas extracting tested in field. Analysis on influencing factors of efficient radium of drilling hole gas extracting, and obtain the influence law on the efficient radium of drilling hole gas extracting.

Abstract: Large strip mining technology could effectively control the surface subsidence inducing from overlying strata movement and realize green mining. Bored stress and deformation sensors were laid in 4301 working face pillar of Shandong energy zibo mining group tangkou coal, analyzing the strip pillar stress pre and post working face; numerical simulation was used to study the influence of overlying strata from reserved size of strip pillar. According to the observation results of surface movement and deformation, law of surface movement and deformation characteristics was studied, which contributed to the practical application of large strip mining technology under deep mining and had the important theoretical and practical significance for mining under buildings ,railways and water in Chinese.

Abstract: broken rock zone is the main reason for the convergence of surrounding rock deformation, and its thickness not only is a reflection of many factors which influence the stability of surrounding rock, but also is the results of the interaction of many factors, a comprehensive classification index. Roadway support design based on classification result of broken rock zone, has a solid theoretical foundation, and the field application effect is remarkable.

Abstract: Based on the green mining concept of coal mine, connotation and technology system of green mining of manganese resources were expound. According to the problems on the mining and utilization procedure of manganese resources, the green mining of manganese was suggested. It included the water preserving mining technology, reducing subsidence mining technology, non-waste mining technology, as well as comprehensive utilization technology of other associated resources. The main key issues were in-depth analyzed in this paper, and the recommendations for the further research and development were proposed.

Abstract: After mining, a dynamic distribution of mining fissure elliptic paraboloid zone in the overlying stratum would be formed. Based on the rock mechanics, seepage flow mechanics, mass transfer theory and elastic-plastic theory, the coal-rock mass deformation equation, mixture gas seepage equation and gas diffusion equation of the mining fissure elliptic paraboloid zone are deduced. Combined with various boundaries, initial conditions, the multi-field coupling mathematical model of mining fissure elliptic paraboloid is obtained. The model provides a theoretical basis for numerical simulation of gas drainage system layout.

Abstract: The paper studied the change of permeability of three different coal seam samples at different injection pressure by using the MYS-I type permeability measuring system of coal and rock samples, according to the problem of the coal permeability highly affected during the seepage process, and also researched the water pressure distribution at the pressure of 4 MPa, 8MPa, and 12MPa based on COMSOL Multiphysics. The results show the permeability of coal samples gradually increases with injection pressure increasing and meets a cubic polynomial variation. The injection pressure range obeys a distribution, water pressure gradually decreases with increasing distance from the hole wall at the constant pressure, the flow velocity also reduces. The injection pressure gradient and the effective range gradually increases with injection pressure increasing, the pressure gradient gradually decreases with increasing distance from the hole wall, the maximum coverage radius of water injection pressure range is about 9.5m.

Abstract: Based on the present situation of heat hazard in deep mine, main cause of geothermal anomaly in Huainan mining area are expounded in detail and cooling techniques adopted in mining coal face with high temperature are analyzed, and cooling experimental studies using U and Y ventilation systems are carried out in adjacent working faces of Guqiao and Dingji coal mines, which shows that the airflow temperature in roadways using Y ventilation system is 3~5 °C lower than that of using U ventilation system and humidity ratio decreases from 95%~100% to about 92%. Finally, research contents and further direction of heat hazard in deep mine are pointed out.

Abstract: Air volume control at wellhead is inconvenience when conduct fan performance test for metal mine We use total return air roadway to adjust conditions, testing air volume at main fan diffuser ,which has advantages with simple operation, security, ventilation recovery fast and so on and test out surface air leakage drag masterly. By analysising the testing process, point out precautions advantages and disadvantages of such test methods which have certain reference value for related test.

Abstract: In order to resolve the supporting problems of the open-off cuts with span of 10m in Tashan coal mine No.3~5 coal seams, this study investigated and analyzed the problems in the current open-off cuts supporting and the supporting parameters, and performed laboratory test and analysis to the coal and rock's mechanical properties. The open-off cut wall rock in Tashan mine has the problem of serious deformation and high possibility of sudden falling. After academic analysis and numerical calculation, a new supporting mode is designed for the supporting of large span open-off cuts: unite high strength anchor bar, combined anchor rope, W steel strip, metal mesh and concrete to form a group anchor seal effect, therefore maintain the tunnel wall rock's stability and safety. Engineering test was conducted at the 8105 working face open-off cuts, the anchor rope's anchorage force changes in the range of 140 ~ 160kN, the maximum delaminating value of the roof in anchorage zone is about 7mm, and the maximum roof-to-floor convergence is 38mm. The result shows that the proposed "anchor bar - combined anchor rope - concrete" supporting model improved the overall bearing capacity of the supporting structure, controlled the tunnel wall rock's deformation effectively, and also achieved the desired effect of the supporting design, ensured the safety of the large section open-off cuts.

Abstract: In this paper, complex summation is applied to the researches on upper mining limit of coal seams. In detail, nature, trend and equivalent fall of a fault are respectively cited as quadrant, angle and size of plain vector coordinates. An equivalent fault is thus acquired through complex ummation and then put on the most unfavorable position to analyze the impact of this fault on results of research on upper mining limit. As a esult, the application has successfully eliminated superimposed impact of minor faults on upper mining limit evaluation