Investigation on Energy Evolution and Storage Characteristic of CSTBD Red Sandstone during Mixed-Mode Fracture

Table 2

Test parameters.

α	Specimen ID	Load at preset unloading level (kN)	Preset unloading level	Loading rate
10°	10-S-1	0.487	0.1	Initial loading and unloading curves: 2 kN/min; Secondary loading curve: 0.1 mm/min
	10-S-2	1.461	0.3
	10-S-3	2.435	0.5
	10-S-4	3.409	0.7
	10-S-5	4.383	0.9
20°	20-S-1	0.488	0.1
	20-S-2	1.464	0.3
	20-S-3	2.440	0.5
	20-S-4	3.416	0.7
	20-S-5	4.392	0.9