The Influence of Heading Rate on Roof Stability in Coal Entry Excavation

Table 6

Results of stress field measurements.

Site	Principal stress	Value (MPa)	Dip angle (°)	Azimuth angle (°)
12311	σ1	35.82	20.5	114.3
	σ2	20.38	67.5	320.3
	σ3	18.39	9.1	207.7
	σv	20.99	0	—
12521	σ1	36.11	11.5	103.5
	σ2	19.13	77.7	263.4
	σ3	18.07	4.1	12.7
	σv	19.80	0	—