Creep Investigation on Shale-Like Material with Preexisting Fissure under Coupling Temperatures and Confining Pressures

Table 3

The axial stress of each loading grade under different confining pressures.

Confining pressure (MPa)	Axial stress (MPa)
	First step (45%∼55%)^b	Second step (60%∼65%)	Third step (75%∼80%)	Fourth step (85%∼95%)
0	3.06	4.08	5.10	6.11
1	8.15	10.19	12.23	14.27
3	12.23	15.29	18.34	21.40
5	16.31	20.38	24.46	28.54
7	22.42	28.54	34.65	—^c

^bThe percentage means the ratio of axial stress of each stage against the strength (three specimens were tested at each kind of confining pressure) at each kind of confining pressure, for example, 45%∼55% means the value of axial stress against strength of the tested specimen at each kind of confining pressure varies from 45% to 55%. The four steps means four loading grades. ^cThe Specimen had damaged before the fourth step.