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

Table 7

Comparison of surface subsidence and damage.

Classification	Cut off the roof pressure to leave the roadway area	Conventional coal mining area	Contrasting condition
Steps to sink (mm)	<5 mm	400–750 mm	Retaining roadway for roof-cutting pressure relief basically eliminate the step sinking
Crack width (mm)	1–3 mm	10–20 mm	Crack width reduction 75%
Crack interval (m)	30–40 m	8–10 m	Fracture density reduction 70%