This paper investigates the combined effect of the vertical component of the input motion and of the weakening effect associated to pore-pressure build-up with reference to a zoned earth dam for which the most recent probabilistic seismic hazard analyses promoted the need of evaluating its seismic performance.

The two effects were studied through advanced plane-strain non-linear dynamic analyses using a finite-difference numerical model calibrated on an accurate geotechnical characterisation. The occurrence of ultimate limit states in the dam embankment is checked using sets of horizontal and vertical input motions properly selected to account for possible frequency coupling with the dam.

The analysis results are presented and discussed in the paper focusing on (i) the main features of the plastic mechanisms temporarily induced by the seismic actions, (ii) the amplification of the horizontal and vertical accelerations acting in the dam body, (iii) the role of the energy and frequency content of the input motion on the magnitude of earthquake-induced permanent displacements, (iv) the combined effect of frequency coupling and non-linear soil behaviour on the overall dam response.

本文针对分区土坝，研究了输入运动的垂直分量和与孔隙压力累积相关的弱化作用的综合作用，针对该土坝，最新的概率地震危险性分析促进了对其地震评估的需求性能。

通过先进的平面应变非线性动力分析，使用在精确岩土特征上校准的有限差分数值模型，研究了这两种效应。极限状态的在坝堤的发生是使用几组适当地选择以考虑与坝可能的频率耦合的水平和垂直输入运动的检查。

分析结果在本文中进行了介绍和讨论，重点是（i）地震作用暂时引起的塑性机制的主要特征，（ii）坝体中水平和垂直加速度的放大，（iii）输入运动的能量和频率含量对地震引起的永久位移的大小的影响；（iv）频率耦合和非线性土壤特性对大坝总体响应的综合影响。