服役环境作用下泥石流拦砂坝结构可靠性经时演化及灾变机理研究

复杂服役环境作用下拦砂坝工程全寿命可靠性的劣化问题已为共识，考虑拦砂坝结构灾变的严重后果，从长期服役的时间视角重新审视拦砂坝工程可靠性的变化机理至关重要。为解决这一科学问题，需要在明确全寿命期拦砂坝圬工材料经时性能变化规律的基础上，对泥石流-拦砂坝互作用的三维流固耦合过程分析手段等难题尝试突破，这是目前研究的薄弱环节。对此，本项目考察沟道环境作用下坝体圬工材料静动态力学性能时变过程，构建描述泥石流灾害动力过程流变特性及泥石流-拦砂坝互作用过程跨尺度特性的三维流固耦合数值计算框架，探明不同寿命阶段的拦砂坝在泥石流冲击下由结构应力应变响应发展到溃坝灾变的失效路径，并采用基于蒙特卡洛方法的工程可靠度理论查明泥石流灾害下的拦砂坝结构失效概率，进而揭示环境因素长期作用下拦砂坝全寿命可靠性经时劣化及灾变机理。研究成果有望为泥石流拦砂坝设计提供依据，并为拦砂坝实施效果后评价及减灾性能维持提供技术支撑。

Temporal degradation of the life-cycle structural performance of debris-flow dams has been widely confirmed at present due to the complex influence posed by the gully environment and hazard event. In view of the severe consequence of dam failure, it is critical and necessary to re-analyze and evaluate their long-term variation of the structural reliability. A key issue that expected to address this problem regards the analysis of three-dimensional, fluid and solid coupling during the interaction process between debris flow fluid and dam structures under environment variation, which remains a scientific challenge in both theoretical and numerical studies currently. In this context, this project aims at the interaction process between debris flow fluid and dam structures and explores the degradation mechanism of the dam structure as functions of environmental variations. First, the temporal variation process with respect to the degradation of dam material performance is explored by both the static and dynamic tests, under the environment of atmospheric corrosion, water soaking, and debris-flow hazard environment where sabo dams set. Second, a three-dimensional numerical model for describing the complex debris-flow rheological behavior is subsequently developed, based on which a multi-scale computational frame for the simulation fluid-solid coupling process is proposed. According to the developed numerical models, the dynamic response and discontinuous structural deformation of the dam under debris flow impact are analyzed. In this way, the temporal variation mechanism on the life-cycle performance and failure process of debris-flow dam structure under the environmental influence can be concluded, as well as the failure probability using Monte-Carlo based structural reliability analysis method. This project benefits the theoretical foundation for evaluating and maintaining the mitigation effect of debris-flow dams.