Abstract This study investigates different methods for generating non-uniform support acceleration at actual topographic sites. The factors affecting the non-uniform excitation of a topographic site include the time delay between the arrival times of incident waves at different soil depths, causing a phase difference, and the coherence function. The existing coherence models are based on data recorded on flat surfaces and are not suitable for surfaces with topographic features. Therefore, in the present study, models of a canyon site subjected to Ricker waves with different predominant frequencies, shear wave velocities, and shape ratios have been developed, and the results of boundary element analyses in the time domain (using the BEMSA code) have been obtained at different elevations on the canyon surface. Then, by conducting a statistical analysis employing the symbolic regression method on the results of numerous presumed cases, the relationships for calculating the time delay between the support responses and the coherence function of V-shaped canyons were obtained. To verify the accuracy of the proposed relationships, the results were compared with the records from the Pacoima Dam site during two different earthquakes and a good agreement was obtained between the results. Eventually, by implementing the proposed relationships in the random vibration method, the non-uniform acceleration of the site was simulated. The results indicate that the proposed relationships have an appropriate level of accuracy for calculating the time delay and the spectral coherence function of V-shaped canyons.

中文翻译：

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一种在地形位置产生非均匀支座激励的新方法

摘要 本研究调查了在实际地形位置产生非均匀支座加速度的不同方法。影响地形站点非均匀激发的因素包括不同土壤深度的入射波到达时间之间的时间延迟，导致相位差，以及相干函数。现有的相干模型基于平面上记录的数据，不适用于具有地形特征的表面。因此，在本研究中，已经开发了受不同主频率、横波速度和形状比的里克波作用的峡谷场地模型，并且时域中的边界元分析结果（使用 BEMSA 代码）在峡谷表面的不同海拔处获得。然后，通过对众多假设案例的结果采用符号回归方法进行统计分析，得到了支撑响应与V形峡谷相干函数之间的时间延迟计算关系。为了验证所提出的关系的准确性，将结果与 Pacoima 坝址在两次不同地震中的记录进行了比较，结果之间取得了良好的一致性。最后，通过在随机振动方法中实现所提出的关系，模拟了场地的非均匀加速度。结果表明，所提出的关系对于计算V形峡谷的时间延迟和光谱相干函数具有适当的精度。