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，罗纳尔多博尔哈，斯坦福大学U。 本研究计划的目的是建立一个数学模型，用于分析地震期间和地震后由侧向流动和反作用引起的大的地面移动问题。该模型是基于两相混合物理论，并涉及到一个有限元代码的发展能够代表饱和土壤的行为之前和液化过程中。在液化之前，土壤是由一个已经验证的有效应力唯象本构模型的基础上的弹塑性公式与非线性运动硬化。在液化过程中，液化的土壤是由一个总应力粘塑性模型，其粘度是从广泛的数值模拟与随机悬浮球。这两种本构模型是在基于乘性塑性的有限变形理论框架内开发的。利用该有限元模型研究了地表大位移产生的机理，包括侧向流动和侧向流动引起的自由地表预测。 两个案例研究被认为是为了验证模型。第一种是将丰浦砂的松散饱和样品浸没在水中，并在动态激励下倾斜，使土壤像粘性流体一样膨胀和流动。第二项研究涉及1995年1月17日地震期间，对Port Island（日本科比市中心附近的填海土地）的井下阵列记录的非线性地面响应进行重新分析，重点关注液化期间这种变化的土壤行为的影响。地面响应模拟假设的条件下，垂直传播的地震波，与一个完整的运动学耦合的三个组成部分的运动。