Development of novel ground improvement technique of soil desaturating by air injection

注空气减饱和土地改良新技术开发

• 批准号: 17360227
• 负责人: OKAMURA Mitsu
• 金额: $ 5.34万
• 依托单位: Ehime University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2005
• 资助国家: 日本
• 起止时间: 2005 至 2007
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17360227/
• 关键词: Seismic retrofit; Liouefaction; Foundation soil; Unsaturated soil; Multi phase flow analysis; Triaxial test; Centrifuge test

Measures preventing earthquake-induced soil liquefaction are of significant importance to mitigate the liquefaction hazards. However, execution costs of currently available technique are generically expensive. An air-injection technique may be a simple, inexpensive alternative-this leads the saturated soils to the desaturated by injecting pressurized air bubbles, resulting in a higher liquefaction strength and the lower susceptibility This project aims at investigate Mowing items which are essential to develop a novel liquefaction countermeasure technique of soil desaturation by air injection.(1)Influential factors of the liquefaction resistance of partially saturated sand are derived from theoretical consideration and effects of the factors are examined through a series of triaxial tests. It was confirmed that the degree of saturation has a significant effect on the liquefaction resistance. It also appeared that the liquefaction resistance depends on the initial confining pressure and … More the initial pore pressure; the higher the confining pressure and the lower the initial pore pressure, the higher the liquefaction resistance of partially saturated sand. A unique relationship between liquefaction resistance ratios and the potential volumetric strain was found, which enable to estimate the liquefaction resistance of partially saturated sand with the effects of the three factors taken into account.(2)A series of centrifuge tests was conducted to investigate seismic behavior of desaturated soil-structure system and effects of desaturation as a liquefaction countermeasure technique. It was confirmed that settlements of the structure on partially saturated sand is much smaller than that of the saturated sand.(3)A series of model tests that simulate air injection into saturated soils using air-injection probes, was conducted to investigate the desaturation mechanism during air injection It was found that the evolution of desaturation is strongly controlled by the vertical and horizontal permeabilities of the soil as well as the injection air pressure. The numerical analyses using a multiphase flow simulator is conducted to describe the evolution of the soil desaturation obtained from the measurements, and to examine the applicability of the model as a prediction tool enabling the evolution of desaturation in situ to be followed with time and space. Predictions show a good agreement with the measurements regarding the rates, magnitudes, distribution of degree of saturation, and airflow rates. Less

预防地震引起的土壤液化的措施对于减轻液化危害具有重要意义。然而，当前可用技术的执行成本通常是昂贵的。注空气技术可能是一种简单、廉价的替代方案——通过注入加压气泡使饱和土壤去饱和，从而获得更高的液化强度和更低的敏感性。本项目旨在研究开发一种新型注空气土壤去饱和液化对策技术所必需的割草项目。(1)部分饱和砂的液化阻力的影响因素来自于 通过一系列三轴试验来检验理论考虑和因素的影响。证实饱和度对抗液化能力有显着影响。液化阻力似乎还取决于初始围压和初始孔隙压力；围压越高、初始孔隙压力越低，部分饱和砂土的抗液化能力越高。发现了液化阻力比与潜在体积应变之间的独特关系，这使得能够在考虑三个因素的影响的情况下估计部分饱和砂的液化阻力。（2）进行了一系列离心试验，以研究去饱和土-结构系统的地震行为以及去饱和作为液化对策技术的影响。证实部分饱和砂上结构的沉降远小于饱和砂上的沉降。(3)通过利用注气探针模拟向饱和土中注入空气的一系列模型试验，研究了注气过程中的减饱和机理。结果发现，减饱和的演变受到土体垂直和水平渗透率以及注入气压的强烈控制。使用多相流模拟器进行数值分析，以描述从测量中获得的土壤去饱和度的演变，并检查该模型作为预测工具的适用性，使原位去饱和度的演变能够随时间和空间的变化而变化。预测结果与有关速率、幅度、饱和度分布和气流速率的测量结果非常一致。较少的

项目成果

Evolution of soil desaturation by air-injection technique and its evaluation via multiphase flow simulation

注空气技术土壤去饱和度的演变及其通过多相流模拟的评估

• 发表时间: 2008
• 期刊: 6^<th> Int. Conf. Case Histories in Geotechnical Engineering (CD-ROM)
• 作者: H. Yasuhara;T. Morito;Y. Kochi and M. Okamura
• 通讯作者: Y. Kochi and M. Okamura

Effect of saturation on liquefaction resistance of sandy soil

饱和度对砂土抗液化能力的影响

• 发表时间: 2006
• 期刊: Third Int. Conf. Urban Earthquake Engineering 1
• 作者: T.Nakai;F.Zhang;M.Kikumoto;H.M.Shahin;H.Takei;M.Niinomi and N.Iwata;M. Okamura and Y. Soga
• 通讯作者: M. Okamura and Y. Soga

Effect on liquefaction resistance of volumetric strain of pore fluid

孔隙流体体积应变对液化阻力的影响

• 发表时间: 2006
• 期刊: Soils and Foundations 46(5)
• 作者: N. Iwata;T. Nakai;F. Zhang T. Inoue and H. Takei;Mitsu Okamura and Yasumasa Soga
• 通讯作者: Mitsu Okamura and Yasumasa Soga

Inexpensive liquefaction countermeasure-Soil desaturatin by air injection

廉价的液化对策-注空气土壤饱和度

• 发表时间: 2006
• 期刊: Tsuchi-to-kiso 54(7)
• 作者: Mitsu;Okamura
• 通讯作者: Okamura

Centrifuge tests on air injection as lequefaction countermeasure

注入空气作为液化对策的离心机试验

• 发表时间: 2007
• 作者: K. Hosokawa;M. Masuda;M. Okamura;R. Igarashi;J. Takemura
• 通讯作者: J. Takemura