Damage Constitutive Model of Mudstone Creep Based on the Theory of Fractional Calculus

摘要

When swelling mudstone, its various mechanical parameters will change significantly. Establish mudstone's fractional calculus creep damage model structure diagram, which describe the extent of damage in rock damage variable. Assumed that the stress level of rock exceeded its the long-term strength and under the condition of mudstone accelerated strain rate loading, nonlinear damage model based on fractional calculus theory was established. Therefore mudstone creep constitutive model considering the accelerated strain rate loading conditions was obtained. The results of constitutive model showed that there appears to be an exponential function between strain and time in the accelerated creep stage. The creep test data were used to verify the proposed model and the results suggested that the fractional order b was the intrinsic parameters of rock mass which could reflect its hardness. During the accelerated creep stage, fractional creep damage constitutive model could describe the stress-strain relationship well.