Stability of a Roadway below a Coal Seam under Dynamic Pressure: A Case Study of the 11123 Floor Gas Drainage Roadway of a Mine in Huainan, China

Table 2

Technical parameters of the integrated monitoring system.

Distributed optical fiber monitoring system		Self-potential monitoring system
Diameter of fiber optic cable (mm)	5	Number of electrodes	32
Strain coefficient (MHz/%)	499.8	Electrode space (m)	1.5
Maximum break force (N)	2350	Effective length (m)	46.2
Strain fiber optic cable type	High-strength metal-based fiber optic cable	Control vertical height (m)	18.79
Effective length (m)	46.2	—	—
Control vertical height (m)	18.79	—	—

Electrode #32, which should be placed outside the monitoring orifice, was also fixed inside the orifice.