Full-stage creep damage model of carbonaceous shale based on damage induced by disturbance load and experimental verification

Abstract Carbonaceous shale weak layers are widely distributed in mine slopes. To better describe the entire shear creep response of carbonaceous shale under disturbance loads such as blasting and earthquakes, a full-stage nonlinear creep damage model induced by disturbance load was developed based on fractional-order theory. This model consists of a Hooke elastomer, a fractional-order Abel dashpot with damage induced by disturbance load, and a nonlinear viscoplastic damage model. It can comprehensively characterize the features of decelerating creep, steady-state creep, and accelerated creep, effectively reflecting the cumulative damage effect of the number of disturbances on rock shear creep. Shear creep tests were conducted on carbonaceous shale under different numbers of disturbances, and it was found that disturbance load significantly influenced its creep deformation and failure characteristics. The parameters of the creep model were identified using the Levenberg–Marquardt algorithm. A comparison with the classical Nishihara model further demonstrates that the fitted results of this model are highly consistent with test data across different numbers of disturbances, shear stress levels, and creep stages, validating the accuracy and rationality of the model. In addition, the model also demonstrates excellent adaptability in simulating the creep behavior of other rock materials under disturbance load conditions, providing methodological support for the long-term stability assessment of mine slopes under disturbance environments.