面板堆石坝地震动最不利输入方向研究

Study on the Worst Seismic Motion Input for Concrete Face Rockfill Dam

面板堆石坝的抗震研究一般都假定地震动振动方向沿坐标轴主轴方向,不考虑地震动振动方向的不确定性;现行的水工规范对地震动的入射方向也未给出明确规定,工程实践中也无统一标准。以某面板堆石坝为例,采用基于等价黏弹性模型的等效线性分析方法,进行了不同地震动输入方向作用下的地震反应分析,研究比较了24个不同地震动输入方向下面板堆石坝的加速度、动位移和主应力反应。结果说明,在确定的场地波作用下,地震动最不利输入方向并不一定是沿坐标主轴方向;场地波作用下,沿240°方向输入地震动作用时大坝的动力反应最大。在工程设计中不考虑地震动输入方向的计算结果会偏于危险,结论可为类似工程抗震设计提供技术依据与参考。

Seismic studies of the rockfill dam generally assumed that the shock vibration direction is the direction of the main axis,without regarding the uncertainty of the direction of vibration;The current hydraulic specification did not give a clear define of the incident direction of the seizmic waves to consider the seismic stability of dams,and engineering practice has no unified understanding.Taking a rockfill dam as example,the equivalent viscoelastic model is used to conduct a seismic response analysis under different seismic input direction consider.The study compared the acceleration,the displacement and the main stress response at 24 different seismic input directions for the rockfill dam.The results show that 240° is the worst seismic input direction.When the input angle is 240°,the dam shake analysis violently and the dynamic stability is worst.On the whole,not consider the direction of the seismic input,the results are unsafe,there are limitations in engineering design.Relevant laws and conclusions presented in this paper can provide the technical basis and reference for seismic design.