Fandamental Study on Liguefaction and Laterel Spread by LAT exporiments and Numerical Simulations

LAT实验和数值模拟液化和横向扩散的基础研究

• 批准号: 13650535
• 负责人: YAMADA Yasuo
• 金额: $ 2.24万
• 依托单位: University of Tsukuba
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13650535/
• 关键词: Liguefaction; Lateral Spread due to Liguefaction; experiment for visualzation; Discrete Element Method; Micromechanies; LAT(Laser-Aided Tomography); 平面ひずみ試験; 流動化; 剛性回復; 粒状体

Since the 1995 Hyogoken-Nanbu earthquake it has been widely recognized that liquefaction-induced lateral spreading may cause severe damage to facilities located in urban coastal areas in Japan. However its mechanism is still unclear because the behavior of liquefied soil is essentially complicated, being controlled by the microscopic behavior of soil particles and the pore water. This research aims to develop both experimental and numerical tools to observe such microscopic behavior of liquefied soils for studying in detail the mechanism of liquefaction-induced lateral spreading.The experimental study consists of three programs. First, a series of hollow-cylindrical torsional shear tests on Toyoura sand was performed under various drainage and loading conditions to show the importance of recovery of shear resistance of liquefied sand. Secondly, a plane-strain compression apparatus, LAT/PSC, was newly developed for visualizing the interior of the specimen using Laser-Aided Tomography technique. Monotonic loading tests using this device brought successfully both macroscopic and microscopic information during shear deformation. Thirdly, visualization of pore fluid motion was attempted by using PIV technique. The combination of LAT and PIV allows us to obtain the information on particle-pore fluid interaction which is essential in liquefaction phenomena.Meanwhile, a series of Discrete Element simulations was also conducted to understand well the deformation mechanism of liquefied sand. Simulations of cyclic simple shear tests under constant volume condition showed that the distributions of both actual and potential contact points characterized the recovery of shear resistance. This implies the necessity for including the evolution law of such contact points in the development of constitutive equation for liquefied sand.

自1995年兵库县南部地震以来，人们普遍认识到，地震引起的横向扩展可能会对位于日本城市沿海地区的设施造成严重破坏。但由于液化土的性状本质上是复杂的，受土颗粒的微观性状和孔隙水的控制，其液化机理至今仍不清楚。本研究的目的是发展实验和数值工具来观察液化土的这种微观行为，以详细研究液化引起的侧向扩展的机理。首先，在各种排水和加载条件下对丰浦砂进行了一系列空心圆柱扭转剪切试验，以显示液化砂抗剪强度恢复的重要性。其次，一个平面应变压缩装置，LAT/PSC，是新开发的可视化试样内部使用激光辅助断层扫描技术。利用该装置进行的单调加载试验成功地获得了剪切变形过程中的宏观和微观信息。第三，利用PIV技术对孔隙流体运动进行了可视化研究。LAT和PIV的结合可以获得液化过程中颗粒-孔隙流体相互作用的信息，同时也可以通过一系列的离散元模拟来了解液化砂土的变形机制。对等体积循环单剪试验的模拟表明，实际接触点和潜在接触点的分布表征了剪切阻力的恢复。这意味着在液化砂土的本构方程的发展中，包括这些接触点的演变规律的必要性。

项目成果

Matsumoto, H., Saomoto, H., Matsushima, T., Yamada,: "Y. DEM simulation of granular fabric change due to liquefaction-induced lateral flow (in Japanese)"38th annual conference of Japanese Geotechnical Society. in printing. (2003)

Matsumoto, H.、Saomoto, H.、Matsushima, T.、Yamada，：“Y. DEM 模拟液化引起的侧流引起的粒状织物变化（日语）”第 38 届日本岩土工程学会年会。

Matsushima, T., Saomoto, H.: "Discrete Element Modeling for Irregularly-shaped Sand Grains"Proc. NUMGE2002 : Numerical Methods in Geotechnical Engineering. 239-246 (2002)

Matsushima, T., Saomoto, H.：“不规则形状沙粒的离散元建模”Proc。

松本優明 ほか: "液状化に伴う側方流動の個別要素法シミュレーション"土木学会第57回年次学術講演会講演概要集. III. 947-948 (2002)

Y. Matsumoto 等人：“与液化相关的横向流动的离散元方法模拟”日本土木工程师学会第 57 届年度学术会议摘要 III 947-948（2002 年）。

Iwata, N,, Matsumoto, H., Matsushima, T., Yamada, Y.: "Estimation of recovery of shear resistance of liquefied soil (in Japanese)"37th annual conference of Japanese Geotechnical Society. 1999-2000 (2002)

Iwata, N,，Matsumoto, H.，Matsushima, T.，Yamada, Y.：“液化土抗剪力恢复的估计（日语）”日本岩土工程学会第 37 届年会。

岩田直泰 ほか: "液状流動化地盤の間隙水圧消散特性及び側方変形特性評価"土木学会第57回年次学術講演会講演概要集. III. 1163-1164 (2002)

Naoyasu Iwata 等：“液体流化土的孔隙水压力消散特性和横向变形特性的评价”日本土木工程学会第 57 届学术年会摘要 III 1163-1164。