A Practical Swelling Constitutive Model of Anhydrite and Its Application on Tunnel Engineering

Table 5

Summary fits of swelling stress-strain changing over time for the swelling constitutive model with consideration of the time effect.

(%)	Parameters				Goodness of fit
	(kPa)	a	B	c	R-square	RMSE	SSE
52.04	1510	150.30	0.3954	0.0125	0.9750	0.0011	9.4820E − 5

Note. Parameter (%) = 52.04% indicates that swelling strain of this type anhydrite is able to reach to 52.04% after complete free swelling.  = 1510 kPa, which indicates that swelling stress under swelling strain inhibited completely of this type anhydrite, is able to reach 1510 kPa. R-square is the coefficient of determination. RMSE (root-mean-square error) is a frequently used measure of the differences between values predicted by a model and the values actually observed. SSE (sum of squares due to error) is used to measure the total deviation of the response values from the fit to the response values. RMSE and SSE values closer to 0 indicate a fit that is more useful for prediction.