Similar Material Simulation Study on Protection Effect of Steeply Inclined Upper Protective Layer Mining with Varying Interlayer Distances

Table 8

Protection angle at the excavation boundary.

Interlayer distance (mm)	Protection angle at the lower excavation boundary, δ3 (°)		Protection angle at the upper excavation boundary, δ4 (°)
	Present results	Results in Provisions	Present results	Results in Provisions
250	78	80	65	70
450	75	80	71	70
650	78	80	65	70