极近距离采空区下部煤层窄煤柱宽度的确定

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。

Determining of Reasonable Width of Narrow Pillar Under Goaf Ultraclose Coal Seams

The numerical simulation method is used to study plastic damage, coal pillar and solid coal side vertical stress and the deformatin of roadway surrounding rock while setting different coal pillar width under the goaf ultra-close to seam being mined. The results show that with the increase of the coal pillar width, the coal pillar central vertical stress increased first, then reduced. The vertical stress of 5~7 m-width coal pillar central is relatively large and the edge vertical stress of 3~5 m width coal column is the smallest. With the increase of the coal pillar width and vertical stress of coal pillar edge the maximum reaches at 7 m coal pillar width, however, the vertical stress of solid coal side changes a litter. By further numerical simulation, the elasto-plastic damage of roadway and surrounding rock deformation performance best when remaining 7 ~9 m coal pillar. The overall evaluation obtains that reasonable width of narrow coal pillar in deep coal seams is 8 m.