基于主余震序列的高拱坝极限抗震能力损失研究

Ultimate seismic capacity loss of high arch dam based on mainshock-aftershock sequences

目前,高拱坝的抗震安全性分析中仅考虑单独主震的作用,而忽略地震中可能伴随发生的多次余震,对高拱坝在主余震序列作用下的动力响应规律尚缺乏充分认识。以大岗山拱坝为例,建立了综合考虑坝体损伤非线性、横缝开合以及半无限地基辐射阻尼效应的拱坝-库水-地基有限元分析模型,并基于耐震时程法(ETA)构建主震-ETA余震序列进行高拱坝非线性动力分析。研究结果表明:ETA的计算结果与增量动力分析法(IDA)具有可比性;高拱坝的极限抗震能力在主震受损情况下将发生损失,且随主震强度增大而损失增加。最后,基于主震-ETA余震序列计算结果给出了大岗山拱坝的极限抗震能力损失曲线。

At present,in seismic and safety analysis of high arch dams,only the action of single mainshock is considered,while multiple aftershocks that may occur adjointly in earthquake are ignored.Dynamic response laws of high arch dam under action of mainshock-aftershock sequences are not fully understood.Here,taking Dagangshan arch dam as an example,an arch dam-reservoir water-foundation finite element analysis model comprehensively considering dam damage nonlinearity,transverse joint opening and closing and semi-infinite foundation radiation damping effect was established.The mainshock-ETA aftershock sequences were constructed based on the endurance time analysis(ETA)to do nonlinear dynamic analysis of high arch dam.The results showed that the calculation results using ETA are comparable with those using the incremental dynamic analysis(IDA);the ultimate seismic capacity of high arch dam will have loss when the mainshock is damaged,and the loss will increase with increase in mainshock intensity.Finally,based on the calculation results of mainshock-ETA aftershock sequences,the ultimate seismic capacity loss curve of Dagangshan arch dam was given.