Surrounding Rock Stability Classification Method of Coal Roadway Based on In Situ Stress

Table 2

Fitting equations between each index and displacement convergence of the coal roadway.

Displacement convergence	Classification index	Fitting relation	Correlation coefficient
	Rrz		R^2 = 0.93
	Rbrz		R^2 = 0.95
	Rfz		R^2 = 0.91
			R^2 = 0.95
	σh		R^2 = 0.91
	N		R^2 = 0.90
	C0		R^2 = 0.92
εh	Rrz		R^2 = 0.90
	Rbrz		R^2 = 0.94
	Rfz		R^2 = 0.91
			R^2 = 0.92
	σh		R^2 = 0.93
	N		R^2 = 0.90
	C0		R^2 = 0.93

N represents the immediate roof backfilled ratio. C₀ represents the main roof first weighting interval.