Site Characterization and Site Response Effects at CSMIP Stations: Tarzana and I-10 near La Cienega

该项目的目的是增加对场地效应的理解，这些影响可能导致1994年加州北岭地震期间在塔扎纳发生的大震动和拉希内加附近的圣莫尼卡高速公路坍塌。在Tarzana的预期结果将对类似地点的地点特征、地形放大和微带化有用。I-10的预期结果将有助于现场特征以及类似地点的高速公路结构的设计和施工实践。结果将被桥梁设计师撕碎。该研究的重点是两个加州强震仪器计划（CSMIP）站点的现场响应：Tarzana和Baldwin Hills（位于La Cienega的圣莫尼卡（I-10）高速公路坍塌附近）。这两个地点的目标是澄清：(1)通过采集和汇编地面和钻孔的地震、地质和岩土工程数据，了解不同地质条件对现场反应的影响；(2)通过使用特别感兴趣的余震记录，该站点在主震强震记录中的贡献是在Tarzana记录的持续和超过1g的高振幅震动的原因，以及局部站点响应效应，可能会放大地震波并造成La Cienega倒塌的I-10高速公路的损坏。采用的方法如下：1。通过标准横波和压缩波速度测量（地面和井下）以及从表面到基岩（或非常坚硬的材料）的钻孔样品阻尼、密度和模量减少的岩土测试来进行现场表征。2.通过计算强震台站和附近站点记录的余震的平滑几何平均傅立叶振幅谱的比值来估计站点响应。对于距离地震距离和方位角相似的站点，频谱比方法可以从震源和路径效应中计算站点响应。3.将一维线性和等效线性模型以及二维非线性模型的现场响应预测与强震记录的实际响应进行比较，以识别现场效应并将其与可能的震源和路径效应区分开来。* * *

9416424 Darragh The aim of this project is to increase the understanding of site effects that may have caused the large shaking at Tarzana and the Santa Monica Freeway collapse near La Cienega during the 1994 Northridge, CA earthquake. The anticipated results at Tarzana will be useful for site characterization, topographic amplification and microzonation at similar sites. The anticipated results at I-10 will be useful for site characterization as well as design and construction practices of freeway structures at similar sites. The results will be shred with bridge designers. The study focuses on the site response at two California Strong Motion Instrumentation Program (CSMIP) stations: Tarzana and Baldwin Hills (located near the Santa Monica (I-10)freeway collapse at La Cienega). The objectives at both sites are to clarify: (1) the effects of different geology on site response by the acquisition and compilation of seismic, geologic and geotechnical data at the surface and from drill holes; and (2) the contribution of the site in strong motion records of the mainshock by using aftershock recordings of particular interest are the causes of the sustained and high amplitude shaking of over 1 g that was recorded at Tarzana, and the local site response effects that may have amplified seismic waves and caused damage at the collapsed I-10 freeway at La Cienega. The following methods are employed: 1.Site characterization through standard shear-wave and compressional-wave velocity measurements (surface and downhole) and geotechnical testing of drillhole samples damping, density and modulus reduction) from surface to bedrock (or to very stiff material). 2.Site response is estimated by calculating the ratio of the smoothed geometric-mean Fourier amplitude spectra from aftershocks recorded at both the strong motion station and nearby sites For stations located at similar distances and azimuths from the earthquake, the spectral-ratio method is olates the site response from source and path effects. 3.Site response predictions from one-dimensional linear and equivalent-linear models and a two-dimensional nonlinear model are compared to actual response from strong motion recordings to identify site effects and separate them from possible source and path effects. ***