Study on Creep Law and Nonlinear Creep Model of Serpentine Marble

Based on the Yanglin Tunnel, a 40 day uniaxial creep test of serpentine marble in the cracked section of the second lining was carried out. The results show that the steady creep rate and the corresponding creep strain law of serpentine marble under different stress conditions are positively correlated with the increase of stress and time. The long-term strength of serpentine marble measured by isochronous stress-strain curve inflection point method is 30 MPa. In this paper, the damage variable is introduced into viscoelastic and viscoplastic processes by using variable order fractional calculus, and a new elasto-viscoplastic creep constitutive model is obtained. The new elastic viscoplastic creep model can well describe the three-stage creep process of serpentine marble. Compared with the traditional Nishihara Model, this model overcomes the disadvantage that it cannot well describe the accelerated creep stage. The number of models is small and the combination is simple. It can be used to describe the deformation law of rock creep process.