The Relationship between Mining-Induced Stress and Coal Gas under an Optimized Support Scheme: A Case Study in the Guanyinshan Coal Mine, China

Table 1

Mechanical properties of bolts [22, 23].

Bolt type	Material of the rod body	Diameter (mm)	Yield load (kN)	Peak load (kN)	Extension (mm)
Equal-strength left-handed ribbed steel bolt without longitudinal reinforcement	BHRB335 (20MnSi)	20	110-115	140-150	310-330
		22	130-140	190-200
High-strength left-handed ribbed steel bolt without longitudinal reinforcement	BHRB400	20	110-118	150-160	360-370
		22	130-145	200-210