Stability Mechanism and Control of Small Coal Pillar in Inclined Thin Coal Seam with Compound Roof
In order to solve the problem of waste of large coal pillar resources and difficult protection of small coal pillar in gob-side entry driving,taking the 2104 working face of Huacaotan Coal Mine of Hongneng Coal Industry as the engineering background,the reasonable width of small coal pillars under the disturbance of inclined thin coal seam mining was studied using the research methods of theoretical analysis,numerical simulation and engineering practice,and the high-strength composite reinforcement support scheme for gob-side entry driving in trapezoidal roadway was given.The results show that the calculation formula of coal pillar width is obtained based on the limit equilibrium theory of rock mass,and the coal pillar width should be greater than 3.35 m according to the actual data of the mine.After the excavation of the roadway,the peak value of the lateral abutment stress will migrate to the deep part of the coal body,and its position will gradually move away from the goaf with the increase of the width of the coal pillar.The peak value of the vertical stress of the coal pillar will increase first and then decrease with the width of the coal pillar,and finally gradually stabilize.When the width of the coal pillar is 5 m,the deformation of the roadway is stable,the deformation is small,the stress of the surrounding rock of the coal pillar is reduced,and there is no plastic zone in the center of the coal pillar.The field practice shows that the deformation of the trapezoidal roadway along the goaf is small by setting 5 cm coal pillar,adopting the method of"two-way fixation of the crossing anchor cable+one beam and three column reinforcement support"in the mining influence section of the roadway,and arranging the support method of deep anchoring of the crossing anchor cable in the gob-side entry driving section,which meets the needs of safe production and has significant economic benefits.
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