Abstract: 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.

Key words: seepage-stress coupling, stability of earth-rockfill dam, nonlinear constitutive model, nu_ merical simulation, slope stability coefficient

摘要： 针对土石坝在水位动态调控下渗流-应力耦合作用诱发的失稳问题，旨在揭示水位骤升骤降过程中边坡稳定性的非线性响应机制及其关键影响因素。基于邓肯张E-B非线性本构模型，结合Geo-studio软件构建渗流-应力全耦合数值模型，实现对稳态渗流场和多物理场的协同求解，分析下游边坡稳定系数时空演变规律。结果表明：骤升工况下稳定系数呈现初期衰减与后期弱恢复的双阶段特征，且抬升速率与劣化程度负相关；骤降工况下则表现为先增后降的非对称响应，其机制源于渗流场滞后效应与基质吸力演化的耦合作用。数值模拟验证了各极端工况下最小稳定系数均高于规范阈值，量化了渗透系数与水位变化速率的协同影响。研究成果拓展了渗流-力学耦合机制的理论认知，并为土石坝动态安全诊断与全生命周期管理提供了理论支撑。

关键词: 渗流-应力耦合, 土石坝稳定性, 非线性本构模型, 数值模拟, 边坡稳定系数