Evolution of Strength Parameters for Sandstone Specimens during Triaxial Compression Tests

Table 4

and k for different values of the plastic internal variable.

(×10^−4)		(MPa)
3	0.167	56.9
6	0.174	60.7
9	0.183	61.8
12	0.189	62.4
15	0.195	62.5
18	0.201	62.3
21	0.204	62.4
24	0.207	62.1
27	0.211	61.6
30	0.214	61.3
33	0.216	60.9
36	0.218	60.6
39	0.221	60.2
42	0.222	59.9
45	0.224	59.5
48	0.225	59
51	0.226	58.7
54	0.227	58.4