Optimization research on the width of narrow coal pillar along goaf tunnel in tectonic stress zone

Based on the 3D modeling techniques and the measurement of in-situ stress, the tectonic stress field in 15111 working face in Huangyanhui coal mine was inversed. Also,the distribution characteristics of vertical stress on coal seam roof,the vertical stress on the coal pillar along the roadway,the horizontal stress of roadway roof and the de- formation of surrounding rock at different positions along the edge of the gob-area in tectonic stress zone were investi- gated. According to the research result,a method of determining the reasonable narrow coal pillar width in gob-side en- try in tectonic stress area was explored,and the narrow coal pillar width in this research was determined to be 6. 5 m.The investigation indicates that the reduction of stress concentration factor at the edge of gob-area in tectonic zone is most obvious in the left side of anticline and the right side of oblique,the vertical stress curve of the narrow coal pillar and horizontal stress curve of roadway roof at the symmetrical position of the anticline and the oblique have a respec- tively similar character,and it becomes more obviously as the coal pillar width increases,at the same time,the vertical stress peak on the narrow coal pillar close to the side of the roadway and the stress curve shows obvious internal and external stress fields as the coal pillar increases. In the tectonic stress zone,the vertical stress peak on the narrow coal pillar tends to the side of the roadway,and the vertical stress field shows obvious internal and external stress fields as the coal pillar width increases. In addition,the tectonic stress also affect the horizontal stress distribution of roadway roof along the gob-side,when the coal pillar width is 4. 0-8. 0 m,the horizontal stress at the roadway roof decreases gradually from the junction of oblique and anticline to the axis of anticline and syncline,and it turns to an increase character as the coal pillar width increases to 9. 0-16. 0 m. The effect of folds on the deformation of surrounding rock is obvious when the pillar width is narrow,the roadway deformation in two sides of the fold show respectively similar character when the coal pillar width is 4. 0-10. 0 m,while the trend changes to share a similar character when the width wider than10. 0 m.