A Practical Swelling Constitutive Model of Anhydrite and Its Application on Tunnel Engineering
Table 3
Summary fits of swelling strain-time of nine samples for the exponential model and the S-curve model.
No
Exponential model: = (1 − e−kt)
S-curve model: = /(1 + at−b)
k
R-square
a
b
R-square
1
0.0055
19.000
0.9082
0.3777
0.5599
0.0079
0.9727
2
0.0081
1.6400
0.8760
1.1290
0.4658
0.0121
0.9839
3
0.0122
0.5943
0.9299
54.370
0.4014
0.2516
0.8806
4
0.0093
1.0900
0.9119
1.0990
0.7054
0.0115
0.9610
5
0.0131
0.7403
0.8310
67.230
0.2789
0.3987
0.9788
6
0.0148
0.3044
0.9412
3.2180
0.5935
0.0215
0.9923
7
0.0157
0.3184
0.9097
138.60
0.3203
0.7320
0.9653
8
0.0253
0.0214
0.9094
196.30
0.4645
0.5360
0.9533
9
0.0239
0.0211
0.9322
194.40
0.4791
0.4666
0.9708
Note. R-square is a number that indicates how well data fit a statistical model and is known as the coefficient of determination. In general, the higher the R-square, the better the model fits data. The above results were obtained using MATLAB Curve Fit Tool.
