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Abstract A computer-controlled creep setup is applied to the triaxial creep tests of the salt rock specimens, which are taken from the Jianghan Oilfield, Hubei Province. Based on the definition of damage variable of rock, which is changing with loading time and obtained from Weibull distribution, a new variable-viscosity Abel dashpot has been proposed. Based on the theory of fractional calculus, the creep damage constitutive model of salt rock is proposed by replacing the Newtonian dashpot in the classical Nishihara model with the new Abel dashpot. Also, parameters in the new constitutive model can be determined by the least-squares fitting analysis. In comparison of fitted curves, it can be manifested that the fractional derivative creep constitutive model proposed in this paper is evidently superior to describe the three creep stages of salt rock, especially the tertiary one. Furthermore, the classical Nishihara model has been proved as a special case of the constitutive model proposed in this paper
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Received: 06 July 2012
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2013, Vol. 34 
