Modeling Two-Dimensional Site Effects at the Treasure Island Downhole Array

Abstract

AbstractNumerous studies have challenged the wide applicability of one-dimensional (1D) ground response analyses (GRAs), seemingly due to the variable subsurface geologic conditions present at most sites. However, while two- and three-dimensional (2D and 3D, respectively) GRAs could be used to overcome these limitations, the lack of site-specific 3D subsurface models and the daunting computational costs of current software are impediments to improved modeling of site effects in engineering practice. In this paper, we aim to address both of these challenges by utilizing: (1) a practical framework called the ‘H/V geostatistical approach’ to develop large-scale, site-specific, 3D shear wave velocity models, and (2) an optimized open-source, finite element software called ‘Seismo-VLAB’ to perform large-scale 2D/3D finite element analyses. The investigations are performed at the Treasure Island Downhole Array (TIDA). By incorporating cross-sections across different lateral extents and azimuths and validating the site response predictions relative to recorded earthquake motions in the downhole array, we show that the site-specific 3D Vs model from the H/V geostatistical approach is capable of replicating wave scattering and more complex wave propagation phenomena observed in the field.KeywordsSite responseSpatial variabilityGround motionsNumerical simulationTreasure Island downhole array