Perturbation-induced delayed shear creep instability in rock Joints: A nonlinear model based on irreversible deformation

Abstract

Weak seismic waves from distant sources may accelerate damage evolution on active faults, triggering delayed unstable slip. Existing models rarely explain the impact of weak perturbations on creep evolution. A nonlinear creep model with damage variables based on irreversible deformation is proposed, quantitatively capturing the perturbation aftereffect defined as accelerated creep evolution induced by weak perturbations. The model captures both the nonlinearity of rock mass creep deformation and the aftereffects of historical perturbations, thereby overcoming existing model limitations in accounting for coupled effects between long-term creep and short-term perturbations. Experimental validation confirms the model quantifies perturbation-induced creep acceleration and describes both instantaneous and delayed post-perturbation instability. By incorporating an irreversible deformation instability criterion, the model quantifies residual creep life of perturbed rock joints, showing substantial life-shortening through accelerated accumulation of irreversible deformation. This provides a novel methodology for analyzing joint creep behavior under complex perturbations environment, offering key insights into earthquake remote triggering and delayed engineering hazards.