Evaluating Long-Term Strength and Time to Failure of Sandstone with Different Initial Damage

Table 9

Model parameters and creep failure time of rock specimens with different initial damage at the creep stress level 27.4 and 29.4 MPa.

Creep stress (MPa)	Initial damage	Strain threshold (%)	E1 (GPa)	E2 (GPa)	η1 (GPa·h)	η2 (GPa·h)	Failure time (h)
27.4	D1	0.55	9.3	80.0	3806.8	141.1	307.23
	D2	0.49					223.85
	D3	0.43					140.51
	D4	0.4					98.82
29.4	D1	0.55	8.3	63.5	2789.9	125.3	132.35
	D2	0.49					84.92
	D3	0.43					27.97
	D4	0.4					4.34