不同材料非线性组合对重力坝抗震能力的影响

Influences of different materials nonlinear combinations on the seismic capacity of gravity dams

抗震能力分析是重力坝抗震设计中的关键环节,地震过程中各类非线性行为耦合机制十分复杂。基于库水-坝体动力相互作用、坝体-地基材料非线性以及钢筋-混凝土耦合作用等非线性行为,组合设立三类仿真分析条件,建立循环荷载下考虑滞回效应的混凝土损伤模型和考虑动态黏结滑移性能变化过程的钢筋混凝土分离式模型,以金安桥重力坝非溢流坝段为例,研究不同材料非线性组合对重力坝抗震能力及失效破坏模式的影响。研究结果表明:在所给定的相同标准谱人工地震波荷载作用下,坝体局部配筋将提升重力坝极限承载能力,且钢筋限裂作用显著,同时钢筋混凝土的相互作用将有效抑制结构失效破坏后的灾变演化加剧;计入地基损伤将进一步提升大坝极限承载能力,坝体的损伤演化路径与损伤分布面积有明显改善;并且坝体-地基系统整体质量和刚度的变化对大坝位移响应幅值影响明显,其中质量与位移响应正相关,刚度与位移响应负相关。

Seismic capability analysis is a key link in the seismic design of gravity dams.However,the coupling mechanism of nonlinear behaviors during the earthquake process is very complex.Three types of simulation conditions were developed relying on the nonlinear behaviors,including reservoir water dynamic interaction,material nonlinearity of dam-foundation and coupled interaction between reinforcement and concrete.A concrete damage model considering hysteresis effect and a separated model of reinforced concrete on the basis of the dynamic bond-slip performance under cyclic loading were established for investigating the effect on the seismic capability and failure mode of gravity dams under different materials nonlinear combinations.The non-overflow section of Jin Anqiao gravity dam was taken as a practical example.The results show that the ultimate bearing capacity of the gravity dam is enhanced by the partial reinforcement of the dam under a given artificial seismic wave load with the same standard spectrum,and the crack limiting effect of the reinforcement is remarkable.Meanwhile,the coupled interaction within reinforced concrete can effectively inhibit the intensification of catastrophic evolution after the failure of the structure.The ultimate bearing capacity of the dam will be further raised by considering the foundation damage,and the damage evolution path and damage distribution area of the dam body will be obviously improved.Moreover,the change of the overall mass and stiffness of the dam-foundation system has obvious influence on the amplitude of the dam displacement response,in which the mass is positively correlated with the displacement response,while the stiffness is negatively correlated with the displacement response.