It is considered that the roof and floor of seam 5 are in poorer steadines,where mudstone prevails,and the roof and floor of seam 6 in better steadiness,where sandstone dominates.

• 5煤顶底板以泥岩分布最广，6煤顶底板砂岩、粉砂岩和泥岩均有较大分布。砂岩稳定性较好，粉砂岩次之，泥岩较差。