Acoustic Emission Monitoring and Failure Precursors of Sandstone Samples under Various Loading and Unloading Paths

Table 3

Fractal values of AE of samples under different stress ratios.

Stress ratio	Scheme I				Scheme II				Scheme III
	10 MPa	20 MPa	40 MPa	50 MPa	10 MPa	20 MPa	40 MPa	50 MPa	10 MPa	20 MPa	40 MPa	50 MPa
0.2	1.51	0.90	1.41	1.31	1.21	0.67	0.67	1.26	0.69	0.73	0.83	0.56
0.4	1.34	0.96	1.21	1.23	1.26	0.69	0.69	0.98	0.63	0.62	0.92	0.98
0.6	1.38	1.01	1.29	1.34	1.03	0.61	0.63	1.19	0.51	0.48	0.90	1.12
0.8	1.12	0.79	1.23	1.31	1.19	0.85	0.85	1.16	0.72	0.54	0.83	1.08
1.0	0.91	0.69	1.51	1.40	0.62	0.30	0.31	1.20	0.31	0.41	0.97	0.98