Study on Temporal and Spatial Characteristics of Overlying Strata in the Deep Coal Mining Process

Table 2

In situ stress test results.

Principal stress	Measured value (MPa)	Azimuth angle (°)	Dip angle (°)	Vertical stress (/MPa)	σi/
σ1	24.79	144.45	3.91	10.8	2.30
σ2	14.55	52.64	24.86		1.35
σ3	9.87	64.8	242.81		0.91