Study on 3D stress evolution characteristics of fully mechanized mining face with knife-handle-type gob-side entry retaining
Taking 1 2-402 working face of Huojitu Coal Mine as research background,combined method of Rhino-Griddle-FLAC3D was used to study the 3D stress field distribution characteristics of gob-side entry retaining affected by mining in Huojitu Coal Mine.The study showed that with the advancing of working face,the pressure of roof rock layer and the secondary stress generated by the structural adjustment of roof rock layer gradually transferred to the coal rock mass in front of the working face and the coal pillars on the gob side,and the larger the coal pillar size,the higher the concentration degree of internal stress in the coal pillar.Based on the stress distribution and transfer characteristics of the l-2-402 working face,it was concluded that when the working face advanced 60 m,it reached the first weighting impact area;when the working face advanced 650-710 m,it reached the first weighting impact area after the working face shrank;the area affected by the initial full mining of the surface was 169-209 m,while the area was 819-859 m after the working face shrank.Based on the 3D stress distribution characteristics of mining,the areas affected by the large-scale roof fracture were the first weighting impact area,the full mining impact area on surface,the first weighting impact area after face shrinking,and the full mining impact area on surface after face shrinking;the expanded area of the roadway section was the intersection area between the roadway and the connecting roadway.The overlapping area between the mining pressure impact area and the roadway intersection area was a key monitoring area.
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