Abstract This paper presents the impact of valley topography on the stability of an earth-rockfill dam slope during earthquakes. The valley site is simplified as an ideal trapezium. A series of three-dimensional numerical models with different valley floor widths and valley wall slopes are used to represent different geometries of the valley topography. A modified dimensionless valley topography coefficient ς is proposed to describe the shape characteristics of the valley topography quantitatively. Considering the most commonly used parameter, the length-height ratio of the dam (L/H), ς replaces L with the length of the median line, Lm, and introduces a shape index, S, as a correction factor on the basis of Lm/H. Comparing to L/H, data from previous studies indicate that ς has a better correlation with the increment ratio of FoS3D to FoS2D. The shear strength reduction technique and the pseudo-static approach are adopted to calculate the factor of safety and the associated critical slip surface of the dam slopes. The results show that the valley topography plays a positive role in the seismic stability of the dam in the cases investigated in this study, especially for narrow valleys and that the valley topography effect will decrease with increasing earthquake intensity.

中文翻译：

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谷地地形对土石坝地震稳定性影响的修正谷地地形系数评价

摘要 本文介绍了地震期间河谷地形对土石坝边坡稳定性的影响。谷地被简化为一个理想的梯形。一系列具有不同谷底宽度和谷壁坡度的三维数值模型用于表示谷地地形的不同几何形状。提出了一种修正的无量纲谷地形貌系数 ς 来定量描述谷地地貌的形状特征。考虑到最常用的参数，大坝的长高比（L/H）， 以中线长度 Lm 代替 L，并引入形状指数 S 作为修正因子流明/小时。与 L/H 相比，先前研究的数据表明 ς 与 FoS3D 与 FoS2D 的增量比具有更好的相关性。采用抗剪强度折减技术和拟静力法计算大坝边坡的安全系数和相关临界滑移面。结果表明，在本研究调查的情况下，山谷地形对大坝的地震稳定性起着积极的作用，特别是对于狭窄的山谷，山谷地形的影响会随着地震烈度的增加而减弱。