Experimental Study on Crack Extension Rules of Hydraulic Fracturing Based on Simulated Coal Seam Roof and Floor

Table 4

Test loading scheme.

Scheme	σ1 (MPa)	σ2 (MPa)	σ3 (MPa)	σ3/σ1
1	3.51	2.92	1.23	0.35
2	3.51	2.92	1.66	0.47
3	3.51	2.92	2.28	0.65