Stability Control of a Roadway Surrounding Rock during the Cutting and Pressure Relief of a Coal-Bearing Roof at a Shallow Mining Depth

Table 5

Key positions and maximum value on the roof separation variation curve.

Roof separation monitoring point	Distance from opening to 12201 sides (m)	Curve increases its starting position (lag face distance) (m)	Curve starts at a smooth position (lag face distance) (m)	Maximum ceiling separation (mm)
No. 6	260	33	81	17.9
No. 5	280	31	82	22.0
No. 4	330	−2	94	17.8
No. 2	430	−48	8	33.4
No. 1	480	−34	−29	58.4