| Aim to the actual situation for incompact fractured surrounding rock, poor wholeness, floor heave serious in certain areas and supporting difficulties when roadway layout in the stress reduction zone in closed in close distance seam coal. With comprehensive research methods of site survey, laboratory test, theoretical analysis, numerical simulation and site industrial application, combining with on-site project, this article analyzes damaging characteristics of upper-coal gob baseboard with different mining heights and different layer thicknesses, as well as its influence to lower-coal gateway stability.Get physical mechanics parameters of coal petrography through test in the laboratory, carry out excavation damaged zone test to both gateways of lower coal by ultrasonic nondestructive testing analyser, get damaging zone characteristics of upper-coal gob baseboard by exploring completeness of lower coal roof, and provide basic for theoretical analysis. By slip-line field theory, figure out damaging scope of upper coal gob baseboard with different mining heights and inferior stress distribution regulation of different coal pillar widths in flexible state. Use numerical simulation analysis software to analyze damaging characteristics of upper coal gob baseboard with different mining heights, analyze different mining heights and coal layer thickness, as well as lower coal gateway stability with different coal pillar widths. The following is the final conclusion:with the increase of mining height, gob damages expand, lower coal gateway roof stability decreases; in flexible state, coal pillar width reduces and lower coal gateway is damaged badly. Classify gateway roof stability according to different mining heights and thickness between coal layers, adjust original supporting parameters of instable and extremely instable roofs, make supporting reasonable economically. Put research achievement into practice and gain favourable effect. |
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