A Nonlinear Statistical Damage Constitutive Model for Porous Rocks

Table 2

Error analysis of the statistical damage constitutive model.

No.	Rock type	Confining pressure (MPa	Water content (%)	Coefficient of determination R^2
				OA section		AB section		CD section		Whole stage
				Refer to Figure 3
				Equation (16)	Equation (28)	Equation (16)	Equation (28)	Equation (16)	Equation (28)	Equation (16)	Equation (28)
1	Sandstone (n = 13.9%)	0	0	—	0.987	—	0.999	—	0.999	—	0.996
2	Sandstone (n = 21.1%)	0	0	—	0.999	—	0.999	—	0.999	—	0.998
3	Sandstone (n = 15.2%)	0	9.88	—	0.956	—	0.999	—	0.991	—	0.990
4	Sandstone (n = 21.3%)	0	6.95	—	0.983	—	0.997	—	0.903	—	0.998
5	Sandstone [38]	0	2.05	—	0.996	—	0.961	—	0.987	—	0.998
6	Sandstone [38]	0	3.41	—	0.984	—	0.995	—	0.989	—	0.999
7	Coal [37]	0	—	—	0.999	—	0.939	—	0.664	0.405	0.994
8	Coal [37]	3	—	—	0.997	—	0.938	—	0.947	0.639	0.998
9	Coal [37]	5	—	—	0.994	—	0.992	—	0.996	0.613	0.999
10	Coal [37]	8	—	—	0.990	—	0.992	—	0.981	0.660	0.998
11	Norite [37]	0	—	—	0.991	—	0.821	0.203	0.833	0.724	0.980
12	Norite [37]	3	—	0.176	0.995	—	0.879	0.627	0.916	0.840	0.988
13	Norite [37]	5	—	0.298	0.995	—	0.894	0.900	0.927	0.896	0.992
14	Norite [37]	8	—	0.371	0.997	—	0.941	0.880	0.970	0.914	0.994
15	Quartzite [37]	0	—	—	0.931	—	0.992	−	0.988	0.673	0.999
16	Quartzite [37]	3	—	—	0.995	—	0.995	0.258	0.939	0.769	0.997
17	Quartzite [37]	5	—	0.05	0.995	—	0.994	0.364	0.960	0.837	0.998
18	Quartzite [37]	8	—	—	0.982	0.127	0.999	0.745	0.980	0.875	0.998
19	Altered rock [36]	4	—	0.581	0.979	0.628	0.997	0.495	0.994	0.914	0.999
20	Altered rock [36]	12	—	0.780	0.781	0.910	0.993	0.940	0.993	0.978	0.997