Reliability Assessment of the San Fernando Dam During the Northridge Earthquake

北岭地震期间圣费尔南多大坝的可靠性评估

• 批准号: 9416469
• 负责人: Sara Lacy
• 金额: $ 6万
• 依托单位: Tufts University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-09-15 至 1996-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9416469&HistoricalAwards=false
• 关键词: Reliability; Assessment; San; Fernando; Dam

9416469 Lacy During the Northridge, CA earthquake, the upstream face of the Lower San Fernando dam spread laterally upstream several feet. Surface cracks and sand boils developed. The documentation of the behavior is during of this during the Northridge earthquake provides an opportunity to validate an existing state-of-the-art method to analyze the seismic stability of earth dams, including the prediction of liquefaction and permanent displacements. Data collected at the Lower San Fernando dam during the Northridge earthquake will be used to assess the reliability of the dam during and after an earthquake event. This will be achieved by generating a sequence of possible realizations of the ground motions and soil properties and analyzing each deterministically using a general two-phase nonlinear finite element procedure. The ground motion at the base of the dam is simulated according to a spectral content derived from measurements at nearby bedrock sites. The material properties pertinent to the occurrence of liquefaction and strength are treated as spatially varying random fields with mean, variance and, where possible, spatial correlation structure derived from actual measurements at the site. The saturated soil in these problems is treated as a two phase continuum of soil skeleton and pore fluid. the porewater and soil skeleton behavior are fully coupled, thereby accounting for the interaction between the two media as the soil deforms. The nonlinear elasto-plastic behavior of the soil skeleton is modeled by multi-yield surface plasticity. for each analysis, time histories of soil response are produced, including accelerations, displacements and pore water pressures. The resulting sequence of soil responses is processed statistically to yield estimates of reliability of the earth dam system. ***

9416469 Lacy在加利福尼亚州北岭地震期间，下圣费尔南多大坝的上游面向上游横向扩展了几英尺。 表面裂纹和砂沸发展。 北岭地震期间的行为文件提供了一个机会，以验证现有的最先进的方法来分析土坝的地震稳定性，包括液化和永久位移的预测。 北岭地震期间在下圣费尔南多大坝收集的数据将用于评估地震事件期间和之后大坝的可靠性。 这将通过生成一系列可能实现的地面运动和土壤特性，并使用一般的两阶段非线性有限元程序进行确定性分析。 在大坝的基础上的地面运动模拟根据来自附近基岩场地的测量的频谱内容。 与液化和强度的发生有关的材料特性被视为空间变化的随机场，其平均值、方差和（在可能的情况下）来自现场实际测量的空间相关结构。 这些问题中的饱和土被视为土骨架和孔隙流体的两相连续体。孔隙水和土壤骨架行为是完全耦合的，从而解释了土壤变形时两种介质之间的相互作用。 土骨架的非线性弹塑性行为采用多屈服面塑性模型。 对于每一个分析，产生土壤响应的时间历程，包括加速度、位移和孔隙水压力。 土壤响应的序列进行统计处理，以产生土坝系统的可靠性估计。 ***