Deficient floor slope Angle of an ore body often needs to dig a drift (or access) in its footwall rock when adopting non-pillar sublevel caving following-vein excavation.
采用沿脉布置的无底柱分段崩落法，当矿体底板倾角不足时，需要在下盘岩石中开掘进路。
2
The feasibility of the protective coal pillar mining in the artificial inclined steep drift in the thick (ultra thick) coal seam of a large slope is discussed.