NUMERICAL ANALYSIS ON MECHANISM OF DEWATERING AS A MITIGATION METHOD AGAINST LIQUEFACTION

NUMERICAL ANALYSIS ON MECHANISM OF DEWATERING AS A MITIGATION METHOD AGAINST LIQUEFACTION
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DOI：
10.21660/2020.66.9407
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发表时间：
2020
期刊：
--
影响因子：
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通讯作者：
Y. Morikawa
Y. Morikawa
中科院分区：
其他
文献类型：
--
作者：
Y. Morikawa

文献摘要

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近年来，大地震引起的液化对世界各地的许多基础设施和房屋造成了严重的破坏。为了保护人们的日常生活和基础设施免受灾害的影响，开发有效的、经济的、可应用于既有房屋的液化对策变得越来越重要。虽然许多研究人员已经开发出了许多液化对策，但大多数都需要大型施工机械，而且造价昂贵，这限制了它们在既有结构中的应用。为此，日本提出了一种液化对策，称为地下水位降低法。这一方法已经付诸实施，对策的构建也已在几年前完成。该方法的目的是通过降低地下水位，将液化层变为非液化层。然而，这种方法的性能还没有得到充分的定量评估。为此，本文采用有限元方法对地下水位下降前后的液化破坏进行了数值分析。计算采用基于旋转硬化弹塑性本构模型的二维土-水耦合有限元-有限差分法。分析发现，由于地下水位的降低，地下水位以下地面的有效应力显著增加，从而提高了地基的抗液化能力，减轻了地基的沉降破坏。
In recent years, liquefaction due to major earthquake caused serious damages to many infrastructures and houses around the world. In order to protect people’s daily life and infrastructure from the disaster, development of effective and economical countermeasure against liquefaction that can be applied to existing houses is becoming increasingly important. Although many liquefaction countermeasures have been developed by many researchers, most of them require large construction machines and are costly, which limits their application to existing structures. For this reason, a liquefaction countermeasure, called as groundwaterlevel decreasing method, has been proposed in Japan. This method has already been put into practice and the construction of the countermeasure has finished several years ago. The purpose of this method is to change a liquefied layer to a non-liquefied layer by lowering the groundwater level. Yet the performance of this method has not been fully evaluated quantitatively. Therefore, in this paper, numerical analysis using FEM method was carried out to evaluate the liquefaction damage before and after the lowering of groundwater level. The calculation is conducted with 2D soil-water coupling finite element-finite difference (FE-FD) analysis based on a rotating-hardening elastoplastic constitutive model. From the analyses, it is found that the effective stress of the ground below under-groundwater level increases significantly because of the lowering of groundwaterlevel, resulting in an increase in resistance to liquefaction and mitigating the settlement damage of ground.