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

Table 6

Key positions and maximum value of the accumulated lower shrinkage of active columns on the change curve.

Measure point	Curve starts at a smooth position (lag face distance) (m)	Maximum shrinkage under the active column (mm)
No. 2	92	217
No. 7	90	120
No. 12	98	29
No. 13	106	102