Thick-Anchored Dual-Layer Locking Supporting Technique in Gob-Side Entry Driving with the Narrow Pillar: A Case Study

Table 2

Comparison of bolt performance parameters commonly used.

Parameters	Diameter (mm)	Length (m)	Yield strength (MPa)	Tensile capability (kN)	Elongation (%)	Pretension (kN)
Rebar bolts	22	2.2~2.5	500	240	20	≤60
Flexible bolts	21.8	3.5~4.3	1600	560	7	250~300