Abstract
In order to eliminate the potential safety hazard of concentrated coal pillar of overlying coal seam occurring in the extraction process of 31201 fully mechanized working face of Shendong Shigetai coal mine, we formulate safety measures for the next extraction by analyzing the pressure data collected by the hy- draulic support in the extraction process. According to research results, there exists irregular room-mining goaf of Coal 22 above Coal 31, and the existing concentrated coal pillar and scattered coal pillar in room-mining goaf parallel to the working face may cause the fully mechanized working face to form secondary roof structure, moreover, the primary reason for large-area roof fall accident is that the concentrated coal pillar of Coal 22 is destroyed and loses stability, thus leading to the dynamic load in the extraction process of Coal 31. We analyze the data of the extraction process of Coal 31 through technical measures such as pressure observation, mi- cro-seismic monitoring, multiple position extensometer inside stratum and surface observation, aiming at the reason for roof fall; and we formulate a set of complete prevention measures, aiming at overlying goaf and ex- traction pressure of this working face, so as to offer effective safety guarantee for the next extraction of this working face and also offer reference for the extraction of similar working faces.
Highlights
Manifestation characteristics of mine pressureThe face roof pressure is not obvious in the first mining stage. It is raised to 458bar when the mining advances to 40.8m and continues 10 cutting circuits
In order to eliminate the potential safety hazard of concentrated coal pillar of overlying coal seam occurring in the extraction process of 31201 fully mechanized working face of Shendong Shigetai coal mine, we formulate safety measures for the extraction by analyzing the pressure data collected by the hydraulic support in the extraction process
(1) The first time is on October 17th, 2013, when the mining face was increased to 360.4m, the supports No 40#–120#showed the large-area roof pressurization
Summary
The face roof pressure is not obvious in the first mining stage. It is raised to 458bar when the mining advances to 40.8m and continues 10 cutting circuits. Rib spalling and safety valve opening (10%) are happened partially; the column subsidence has not been found; the pressure drawing pace is 48.6m. Several phenomena occur when the roof pressure coming, such as fracture, rib spalling, roof slag dropping, stone leak, safety valve opening rate which is between 5%– 15%, and the column subsidence which is less than. By the end of December 16th, 2013, the mining face had been increased to 773m During this period, the pressure had showed 3-times peaks. (1) The first time is on October 17th, 2013, when the mining face was increased to 360.4m, the supports No 40#–120#showed the large-area roof pressurization. Because there existed irregular 22 coal room collection above the stope face for 37m (it’s 9.25 times the mining height) based on the analysis. The broken equipment and parts including 200 columns, balance cylinders, sprag rams, 484 safety valves, 206 pressure gauges, and other 100 valve blocks, 1000 parts and structural components, 1200 pipe connecting parts. 2.2 Cause analysis of abnormal pressure that occurs on working face The abnormal pressure occurs on working face for
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