| Rockburst is one of the coal mine rock dynamic disasters.It has many influencing factors and complex mechanism.It is one of the research difficulties and hotspots in rock mechanics and mining engineering.Based on the research background of the 7 and 9 coal seams in the 74102 working face of Zhangshuanglou Coal Mine,this paper comprehensively adopts theoretical analysis,numerical simulation,laboratory test and on-site monitoring to study the mining stress distribution and evolution law in the coal seam merged area.The causes of rockburst,monitoring and early warning and prevention and control technologies were comprehensively studied and applied on site.Based on the geological and production technical conditions of the 74102 working face,the influences of the combination of the 7 and 9 coal seams on the mining stress distribution and the impact ground pressure were analyzed.The rockburst risk of the coal seam consolidation area was evaluated,and the impact risk of the level and scope of influencec oal seam consolidation area was determined..Using FLAC3 D numerical simulation software,the stress distribution and evolution law of coal seam in the coal seam merged area were simulated.The results show that the coal seam consolidation area of 74102 working face in Zhangshuanglou Coal Mine increases with the thickness of the bottom coal,and the peak stress and stress concentration coefficient of the coal seam increase.The impact area of the coal seam consolidation area is about 50 m.In the simulated mining process,the average vertical stress peak of the coal seam with a thickness of 6m in the coal seam consolidation area is 1.18 times that of the bottomless coal area,and the average vertical stress peak of the transportation roadway is 1.13 times that of the bottomless coal area.It is 1.06 times of the bottomless coal area;the average vertical stress peak of the coal seam with the bottom coal thickness of 8m is 1.26 times of the bottomless coal area,and the average vertical stress of the transportation road floor is 1.15 times of the bottomless coal area.The vertical stress peak is 1.1 times that of the bottomless coal zone.The stress concentration factor of the working face is up to 4.75,and the elastic energy is easily accumulated in the coal seam,which leads to the occurrence of high energy rupture vibration and rockburst.Aiming at the large thickness of coal at the working face and the roadway,it is easy to appear impact.It is proposed to implement remote high-pressure water injection softening and anti-shock technology in the roadway to the bottom coal area of the working face.The laboratory carried out experimental research on the physical and mechanical properties and fracture mode of bottom coal under different water injection parameters.Through the acoustic emission characteristics test of coal with different water content,it is concluded that with the increase of water content of coal sample,the uniaxial compressive strength of coal sample decreases and the elastic modulus decreases;the relationship between the incident rate,stress and strain of coal and rock acoustic emission has good consistency;the cumulative ringing of acoustic emission is negatively correlated with the moisture content of coal.When the water content of the test coal sample is 2.41%,the uniaxial compressive strength of coal rock is the smallest,the event rate and ringing count are relatively small,and the softening effect of coal rock mass is the best.This provides a theoretical basis for remote high pressure water injection and erosion design and parameter optimization of 74102 working face coal seam.Based on theoretical analysis,numerical simulation and laboratory tests,the technical system for prevention and control of rock-burst in the coal seam of 74102 working face was established,and the remote high pressure water softening technology of coal at the working face was formed,and the deep hole blasting pressure relief in the coal seam of the roadway was formed.Technology and large-diameter drilling pre-relieving technology is the main comprehensive treatment plan for impact ground pressure.Through the microseismic monitoring,the time-space evolution law of the vibration in the coal seam merged area was studied,and the microseismic index was used to test the effect of pressure relief and danger in the dangerous area of rockburst.On-site practice verified the rationality of theoretical analysis results and prevention and control technical parameters,and ensured the safe recovery of the working face.The research results of the thesis effectively guide the safe recovery of the 74102 working face,which can provide theoretical support and technical reference for the similar coal seam merging area or the thick coal seam stratified mining anti-shock.The paper has 128 pictures,11 tables,and 80 references. |
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