Modeling Lateral Flow and Liquefaction-Induced Ground Movement

模拟横向流和液化引起的地面运动

• 批准号: 9613906
• 负责人: Ronaldo Borja
• 金额: $ 23.86万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-10-01 至 2002-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9613906&HistoricalAwards=false
• 关键词: Modeling; Lateral; Flow; Liquefaction; Induced

ABSTRACT: CMS-9613906, Ronaldo Borja, Stanford U. The objective of this research program is to develop a mathematical model for analyzing the problem of lateral flow and liquefaction-induced large ground movement during and following an earthquake. The model is based on a two-phase mixture theory, and involves the development of a finite element code capable of representing the behavior of saturated soils prior to and during liquefaction. Prior to liquefaction, the soil is represented by an already- validated effective-stress phenomenological constitutive model based on an elastoplastic formulation with nonlinear kinematic hardening. During liquefaction, the liquefied soil is represented by a total-stress viscoplastic model whose viscosity is determined from extensive numerical simulations with random suspensions of spheres. The two constitutive models are developed within the framework of a finite deformation theory based on multiplicative plasticity. The resulting finite element model is used to study the mechanism of liquefaction-related large ground displacement, including the lateral flow and prediction of the free ground surface resulting from such flow. Two case studies are considered in order to validate the model. The first involves a loose saturated sample of Toyoura sand submerged in water and sloped inside a test subjected to dynamic excitation, causing the soil to liquefy and flow like a viscous fluid. The second study involves a re-analysis of the nonlinear ground response recorded by a downhole array in Port Island (reclaimed ground near downtown Kobe City, Japan) during the earthquake of January 17, 1995, focusing on the impact of this changed soil behavior during liquefaction. The ground response is simulated assuming a condition of vertically propagating seismic waves, with a full kinematical coupling of the three components of motion.

摘要：CMS-9613906，Ronaldo Borja，StanfordU。该研究计划的目的是开发一种数学模型，用于分析地震期间和之后的侧向流和液化引起的大地面运动的问题。该模型基于两相混合理论，涉及能够在液化之前和期间代表饱和土壤行为的有限元代码的发展。在液化之前，土壤由基于非线性运动学硬化的弹性塑料制剂的已经有效的有效的现象学组成型模型表示。在液化过程中，液化的土壤由一个全应力的粘塑性模型表示，其粘度是由带有球体随机悬浮液的广泛数值模拟确定的。两个本构模型是在有限变形理论的框架内开发的，基于乘法可塑性。所得的有限元模型用于研究与液化相关的大地面位移的机理，包括侧向流量和由于这种流量导致的自由地面的预测。 为了验证模型，考虑了两个案例研究。第一个涉及浸入水中的Toyoura砂饱和样品，并在受到动态激发的测试中倾斜，使土壤像粘性液一样液化和流动。第二项研究涉及对1995年1月17日地震期间波特岛（Port Island）的一个井下阵列记录的非线性地面反应的重新分析（日本科比市市区附近的地面），重点介绍了这种液化期间这种土壤行为的影响。假设在垂直传播地震波的条件下，进行了地面响应，并具有全部运动耦合的三个运动组成部分。