| Shi Ge Tai coal mine 3-1 2 panel mining area overlying the fully mechanized mine goaf,tianlong coal mining area and entity and with complicated mining conditions.31201 fully mechanized working face in pushing under 15.5 m coal mined-out area,the sudden cut top,many sets of stents were killed,stent pressure gauge pressure stable display instantaneous pressure value in 45-80 MPa.In order to avoid the Shi Ge Tai coal mine 3-1 second panel mining again appear similar disasters and accidents,and protect the safety of mine production,the mine in 31201,31202-1 face by room mining coal mined-out area to study the rule of mine pressure appear,provide reasonable dynamic load pressure control technology measures.Through analysising of working face pressure to step distance,length of continued to pressure energy index and microseismic events,geting strength relationship in different regions in 31201 working face as follows: compressive strength of after concentrated coal pillar a large area > compressive strength of room 2-2 coal pillar goaf areas lower recovery > compressive strength of Liu Gen ditch uphill section > compressive strength of area at ordinary times before and after focus coal pillar;Strength relationship in different regions in 31202-1 working face is:compressive strength of the room pillar goaf segment > compressive strength of excessive mining extents > compressive strength of longwall goaf segment > compressive strength of entity coal section.In 31201 and 31202-1 working face surface for surface movement observation,analysis of working face advancing surface subsidence rule of different position,according to data analysis such as the starting distance and impact angle in advance,get the overlying coal seam mining and fully mechanized area for room and flourishing the index significantly greater than the upper coal seam mining area for the entity coal area.Using borehole TV observation,under the condition of understanding has not been affected by the 31201 working face mining 2-2 coal roof integrity,to determine whether 2-2 coal after the roof collapsed through the earth's surface;By analyzing multipoint displacement sensor data,can be given when room and pillar mining,2-2coal began move ahead of working face roof around 30 m;Did not appear after blasting coal pillar caving,eliminate working face of coal large strong dynamic pressure risk.Advance affect the average distance is 36.8 m,within the scope of 21.2 m the pressure increase is relatively obvious,forepole distance set at about 25 m is reasonable.Using numerical simulation software FLAC3 D,concentrated coal pillar caving ahead working face about 12 m,the transfer of stress lead to instability of large area,coal pillar overlying new load significantly higher load-carrying capacity.Support working resistance frequency analysis is: during normal mining in 31201 working face basically meet can be required,but in some special roof structure under the condition of surplus coefficient is too small,and supporting ability is small;31202-1working face shows overall stent stress ideal,stents can satisfy the requirement of the supporting.Single rotary rock structural mechanics model is set up,and calculation formula of the whole frame support working resistance of shallow buried coal seam under the single rotary rock structure is get and working resistance calculation formula of different roof strata structure under the condition of the corresponding support.According to the number of microseismic events,total energy and mine pressure monitoring results for many times,in combination with a wide range of overlying strata movement the macroscopic observation,conclude that working face pressure warning index;Put forward four kinds of method to control dynamic load pressure,finally chose the blasting method to control coal,greatly reducing the inching face goaf coal pillar of dynamic pressure intensity,lifted the risk caused by the coal crushing. |
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