强震作用下面板堆石坝跨尺度面板开裂演化分析
Cross-scale crack evolution analysis for face slab in concrete faced rockfill dams under strong earthquake
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摘要: 准确定位面板薄弱区域、定量评价面板破坏程度对面板坝抗震安全评价至关重要。联合非完全点对点界面和四分树网格生成技术,实现了面板坝面板与垫层接触作用的两级跨尺度精细化建模;引入混凝土黏聚力模型并联合筑坝材料广义塑性模型、状态相关的弹塑性接触面模型考虑材料强非线性和破坏过程,建立了强震作用下面板动力弹塑性跨尺度开裂演化分析方法,并研发了显式地震波动分析框架下的SBFEM-FEM耦合计算软件。以200 m级面板坝为例进行了面板动力破坏数值分析,并分别考虑了面板配筋率、竖向地震和坝前水深的影响。结果表明:十分直观地再现面板坝防渗面板的动力开裂演化过程,有助于定位面板局部薄弱区域、定量评价面板破坏程度以及评估抗震措施加固效果,为混凝土面板抗震优化设计和极限抗震能力评估提供技术支持。可拓展用于其它混凝土防渗结构破坏计算,且可容易地扩展至三维分析应用。Abstract: It is crucially important for seismic safety evaluation of high concrete faced rockfill dams (CFRDs) to accurately locate the weak area of the panel and to quantitatively assess the damage of the face slab. In this study, the cross-scale model for CFRD is established using the interface element with asymmetric nodes and Quadtree for refined simulation of slab and cushion interaction. The cohesive zone model for concrete, the generalized plastic model for rockfill and the state-dependent elasto-plastic interface model are combined and used to describe the strong nonlinearity and failure process. On the above basis, the cross-scale crack evolution analysis method under strong earthquake is established and the coupled SBFEM-FEM analysis software is developed in the explicit earthquake wave motion input method frame. The dynamic failure analyses of slabs are performed for a 200-m-high CFRD considering the reinforcement ratio, vertical earthquake and water level of reservoir. The results indicate that the developed method can visually represent the seismic cracking evolution, conveniently locate weak areas of face slab, quantitatively determine the damage severity, and evaluate the aseismic measures. The research results may provide an effective method for the aseismic design and assessment of ultimate aseismic capacity of concrete slab. The proposed method can be extended to the failure analyses of other concrete structures and three-dimensional investigation and application easily.