Research on the width of coal pillar in the face of impact danger under the overlying partial goaf

In order to study the layout of coal pillars in the working face with impact risk under the overlying partial goaf, the coal pillar impact risk and reasonable width in the working face are studied by field monitoring, numerical simulation and theoretical analysis with the I010203 working face as the engineering background.The numerical simulation and field monitoring results show that during the mining process of I010203 working face, the microseismic events in the 15 m wide section of coal pillar are frequent and the energy is released violently, which increases the impact risk of working face.Moreover, the 15 m wide coal pillar can not be completely destroyed after the mining face, but can still bear the higher stress and transfer to the lower coal seam, which increases the impact risk of the mining face of the underlying coal seam.The numerical study shows that when the width is 0-6 m, the coal pillar crushing degree is higher, which is not conducive to the isolation of goaf and the stability of roadway.When the width is greater than 10 m, the elastic core zone appears in the coal pillar, the stress increases rapidly and the impact risk increases.8 m wide coal pillar is the critical coal pillar width that can not only isolate goaf to prevent gas, but also minimize stress and reduce impact risk.A more reasonable coal pillar width is about 8 m.The research results can provide a theoretical basis for setting the width of coal pillar in the joint working face and similar working face.