Aiming at the instability of earth-rockfill dam induced by seepage-stress coupling under dy_ namic regulation of water level

the nonlinear response mechanism of slope stability and its key influenc_ ing factors are revealed. Based on Duncan-Chang

s E-B nonlinear constitutive model and Geo-studio software

a fully coupled seepage-stress numerical model is constructed. Typical working conditions

such as sudden rise and sudden drop of water level

are selected to realize the collaborative solution of steady seepage field and multiphysics

and the temporal and spatial evolution law of the downstream slope stability coefficient is analyzed. The results show that the stability coefficient exhibits two-stage characteristics of initial attenuation and late weak recovery under the condition of sudden rise

and the rise rate is negatively correlated with the deterioration degree. The sudden drop condition shows an asym_ metric response of first increasing and then decreasing

and its mechanism stems from the coupling effect of the lag effect of seepage field and the evolution of matrix suction. Numerical simulation has verified that the minimum stability coefficient under each extreme condition is higher than the standard threshold

and has quantified the synergistic effect of permeability coefficient and water level change rate. The research results expand the theoretical understanding of seepage-mechanics coupling mechanism

and provide theoretical support for dynamic safety diagnosis and life cycle management of earth-rockfill dams.