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采用数值模拟的方法,研究了极近距离煤层群下煤层工作面沿空掘巷留设不同宽度煤柱时巷道的塑性破坏、煤柱和实体煤侧垂直应力、巷道围岩变形情况。结果表明:随着煤柱宽度增加,煤柱中央的垂直应力呈现先增大、后减小趋势,其中5~7 m宽度煤柱中央的垂直应力相对较大,3~5 m宽度煤柱边缘垂直应力最小。随着煤柱宽度增加煤柱边缘垂直应力不断增大,在煤柱宽度达到7 m时最大,而实体煤侧的垂直应力相对变化不大。进一步的数值模拟研究表明,巷道的塑性破坏程度、围岩变形量在留设7~9 m煤柱时效果最佳。综合考虑得出了下煤层开采护巷窄煤柱的合理留设宽度为8 m。
The numerical simulation method was used to study the plastic failure of roadways along the roadway with coal pillars of different widths under the roadway driving along the coal seam under the extremely close coal seam group. The vertical stress of the coal pillar and the solid coal side and the deformation of surrounding rock of the roadway were studied. The results show that with the increase of coal pillar width, the vertical stress in the center of coal pillar first increases and then decreases, and the vertical stress in the center of 5 ~ 7 m width coal pillar is relatively large. The vertical stress of 3 ~ 5 m width coal pillar Vertical stress is the smallest. With the increase of coal pillar width, the vertical stress at the edge of coal pillar continuously increases and reaches the maximum when the coal pillar width reaches 7 m, while the vertical stress on the solid coal side has relatively little change. Further numerical simulation shows that the degree of plastic failure and the deformation of surrounding rock are the best when leaving 7 ~ 9 m coal pillar. Considering synthetically, the reasonably reserved width of narrow coal pillar in retaining lane of next coal seam mining is 8 m.