Topographic Amplification of Seismic Motion: Observations and Simulations in 3D

这笔赠款为开发计算工具提供资金，这些工具将允许进行大规模数值模拟，以研究2D和3D凹凸地形特征的响应。使用这些工具，将进行系统的参数调查，以量化的作用，地形地貌的几何形状，地层，土壤非线性和地面运动特性的网站response。数值预测将通过与来自3D阵列的已发表的现场数据进行比较来验证，这些阵列是专门部署来评估地形放大效应的。最后将把数值计算结果和现场观测结果汇编起来，以发展工程设计实践中计算地形影响的简化程序。如果成功的话，这项工作的结果将影响全国的工程设计实践。虽然地震危险性评估和小区划研究越来越多地依赖于波动模拟，但迄今为止的大多数发展都没有考虑地形特征，从而笼统地假设地球表面是平坦的。然而，对大地震的观测表明，强烈地形起伏的存在会显著加剧强震运动的灾难性后果。这些地形对场地响应的影响可能无法通过广泛采用的平面模型进行预测，这项工作将导致下一代考虑局部地形的波浪运动模拟工具。此外，这项工作将有助于开发一般特征的设计地形放大系数，以超过现有的现场放大系数，并考虑地面运动的地形放大。

This grant provides funding for the development of computational tools that will allow large-scale numerical simulations to be conducted to study the response of 2D and 3D convex and concave topographic features. Using these tools, a systematic parametric investigation will be performed to quantify the role of topogra­phic geometry, stratigraphy, soil nonlinearity and ground motion characteristics in site res­ponse. Numerical predictions will be validated via comparison with published field data from 3D arrays, speci­fically deployed to evaluate topographic ampli­fication effects. Numerical results and field observations will be finally compiled to develop simplified procedures for accounting of topography effects in engineering design practice.If successful, the results from this work will impact engineering design practices nationwide. While seismic hazard assessment and microzonation studies rely increasingly on wave motion simulations, most developments to date do not account for topographical features, making the sweeping assumption of a flat earth surface model. Observations from large earthquakes, however, have shown that the pre­sence of a strong topographic relief can significantly aggravate the catastrophic conse­quences of strong seismic motion. These effects of topography on site response may not be predicted by the widely employed flat surface models, and this work will lead to a next generation of wave motion simu­lation tools that take into account local topography. In addition, this work will contribute to the deve­lopment of design topographic amplification factors for generic features, to be implemented in excess of existing site amplification factors, and account for the topographic aggra­vation of ground motion.