基于耐震时程法的特高拱坝极限抗震能力研究

Ultimate aseismic capacity of ultra-high arch dam based on endurance time method

在对300 m级特高拱坝进行抗震安全评价时,常常面临着工程条件复杂、有限元模型自由度数目多、计算耗时较长、效率较低等问题。为了提高分析效率,节约计算成本,采用了耐震时程法来分析特高拱坝及坝基的动力损伤行为,并进行极限抗震能力研究。基于耐震时程法理论,以《水电工程水工建筑物抗震设计规范》中的标准反应谱为目标谱,采用非线性最小二乘法生成精度较高的3条耐震时程曲线。以我国西南地区某300 m级特高拱坝为例,建立了坝体—基岩三维非线性有限元分析模型,并同时考虑地震动的输入、坝体及基岩的损伤开裂、横缝的动态开合等关键问题。通过考察拱冠梁最大相对位移、横缝最大开度、坝体损伤体积比、损伤耗能等指标来综合评价大坝的极限抗震能力。结果表明,耐震时程法能够很好的反映出特高拱坝在不同强度地震动作用下的动力响应,且计算效率较高。

When evaluating aseismic safety of 300 m ultra-high arch dam,it often faces problems of complex engineering conditions,many DOFs of finite element model,longer calculation time and lower efficiency.Here,to improve analysis efficiency and save calculation cost,the endurance time method was used to analyze dynamic damage behavior of ultra-high arch dam and its dam foundation,and its ultimate seismic capacity was studied.Based on the theory of the endurance time method,taking standard response spectrum in the“code for aseismic design of hydraulic structure”as the target spectrum,3 endurance time curves with higher accuracy were generated with the nonlinear least square method.Taking a certain 300 m ultra-high arch dam in Southwest China as an example,the 3-D nonlinear finite element analysis model of its dam body-bedrock was established,and key problems,such as,input of ground motion,damage and cracking of dam body and bedrock,and dynamic opening-closing of contraction joints were considered at the same time.The ultimate aseismic capacity of the dam was comprehensively evaluated by investigating the maximum relative displacement of crown cantilever,the maximum opening of contraction joints,damage volume ratio of dam body and damage energy consumption.The results showed that the endurance time method can well reflect dynamic responses of ultra-high arch dam under different intensity ground motions,and its calculation efficiency is higher.