Abstract The geometry and flexibility of a canyon are the parameters that greatly affect the value of natural periods in earth dams. The canyon surrounding dams can be assumed as an unbounded domain. To take into account these two effects, the canyon was modeled by SBFEM and the earth dam, which has limited geometry, by FEM. The hybrid technique of SBFEM-FEM for dynamic three dimensional analysis of soil-earth dam interaction was validated with available results in the literature. Because the dynamic-stiffness matrix of the unbounded domain is complex and frequency dependent, the classical mode-superposition method is not straightforward for the soil-structure interaction system. Thus, to obtain the fundamental natural frequency, the dam was excited in the upstream-downstream direction. The natural period of the earth dam for canyons with different geometry shapes and impedance ratios were obtained. They were found to have significant effects on the natural period. The results were compared with actual recorded data. It was found that the proposed graphs in this study may be used by practical engineers for the estimation of natural periods of earth dams in canyons with different shapes and material properties.

中文翻译：

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用 3D 耦合 FEM-SBFEM 估算土坝-柔性峡谷系统的自然周期

摘要 峡谷的几何形状和柔韧性是影响土坝自然周期值的重要参数。大坝周围的峡谷可以假设为一个无界域。考虑到这两种影响，峡谷采用 SBFEM 建模，而具有有限几何形状的土坝采用 FEM 建模。用于土-土坝相互作用动态三维分析的 SBFEM-FEM 混合技术得到了文献中可用结果的验证。由于无界域的动力刚度矩阵是复杂的且依赖于频率，经典的模式叠加方法对于土 - 结构相互作用系统并不简单。因此，为了获得基本的固有频率，在上下游方向上对大坝进行激励。获得了不同几何形状和阻抗比的峡谷土坝自然周期。人们发现它们对自然周期有显着影响。结果与实际记录的数据进行了比较。结果发现，本研究中提出的图表可被实际工程师用于估计具有不同形状和材料特性的峡谷中土坝的自然周期。