Experimental Study on Creep Behavior and Crack Evolution of Stratified Structural Sandstone under Segmental Constant Load

Table 3

Statistical results of constant load experimental parameters.

Sample number	Duration t (h)	Stress σ (MPa)	Crack initiation stress ratio ()	Crack damage stress ratio ()	Driving stress ratio ()	Condition
USN-1	240.0	20.3	1.11	0.63	0.51	Undamaged
USN-2	120.3	22.8	1.24	0.70	0.57	Damaged
USN-3	108.7	25.4	1.38	0.78	0.63	Damaged
USN-4	94.2	27.9	1.52	0.86	0.70	Damaged
USN-1	240.0	16.1	0.87	0.50	0.40	Undamaged
USN-2	186.3	20.0	1.10	0.62	0.50	Damaged
USN-3	117.8	24.1	1.31	0.74	0.60	Damaged
USN-4	86.2	28.1	1.42	0.87	0.70	Damaged
USN-5	4.8	32.4	1.76	1.00	0.80	Damaged
USN-6	1.7	36.1	1.96	1.11	0.90	Damaged