SGER: Air Entrapment for Liquefaction Mitigation

SGER：用于缓解液化的空气滞留

• 批准号: 0234365
• 负责人: M. K. Yegian
• 金额: $ 5万
• 依托单位: Northeastern University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-01 至 2004-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0234365&HistoricalAwards=false
• 关键词: SGER; Air; Entrapment; Liquefaction; Mitigation

0234365, Mishac Yegian, Northeastern University"Air Entrapment for Liquefaction Mitigation"This action is to support a study of the scientific and technical feasibility of an innovative approach for mitigating soil liquefaction.Liquefaction-induced damage to the built environment can be catastrophic. During the past four decades, intensive efforts have been made to understand the mechanism of liquefaction, and to develop procedures for analyzing the liquefaction potential at a site during a given seismic event. While research on liquefaction continues, geotechnical engineering practice has developed various techniques for site improvement that can mitigate the potential effects of liquefaction. Such mitigation measures are expensive, and often can only be utilized for a new project. Mitigating the liquefaction-induced damage to an existing structure in an urban community remains a major challenge.The concept is to introduce air in a saturated sand deposit to increase its resistance against liquefaction. Laboratory and field experiences suggest that only slight amounts of air in the voids of otherwise fully saturated sands (enough to reduce the degree of saturation by 1 to 2%) can significantly increase the liquefaction strength, and decrease the shear wave velocity. Hence, through air entrapment, a new or an existing site can potentially be improved to resist liquefaction, and through shear wave velocity measurements, its adequacy can be verified.The research has a number of specific objectives that are aimed at providing a preliminary understanding of the behavior of air-entrapped sands, and of identifying important areas for future research that would be needed to advance the concept to a fully developed and practical measure for liquefaction mitigation. The objectives of the research can be stated in the form of questions as follows:1. How can air be introduced in loose saturated sands?2. How can samples of varying degrees of saturation (from 95 to 100%) be prepared?3. How can the degree of saturation be measured accurately (up to 0.1%)?4. How will air entrapment affect the liquefaction strength?5. How are other soil properties influenced by the presence of air?6. How does the grain size distribution and angularity of the sand influence the above results?7. How long can air stay trapped under different flow gradients?The research will be a significant contribution to the development of cost-effective measures for liquefaction mitigation. It will also have a broader impact on improving the ability to reduce the expected losses to a community from an earthquake. The research will draw upon the expertise in the geo-environmental field that uses air injection for remediation.

0234365，东北大学米沙克·耶吉安“空气捕集缓解液化”这一行动是为了支持一项关于缓解土壤液化的创新方法的科学和技术可行性的研究。液化对建筑环境造成的破坏可能是灾难性的。在过去的四十年里，人们一直在努力了解液化的机制，并开发出在给定地震事件期间分析场地液化势的程序。随着液化研究的继续，岩土工程实践已经开发出各种场地加固技术，可以减轻液化的潜在影响。这样的缓解措施代价高昂，而且往往只能用于新项目。减轻液化对城市社区现有结构的破坏仍然是一个重大挑战。其概念是在饱和沙层中引入空气，以增加其对液化的抵抗力。实验室和现场经验表明，只有在完全饱和的砂土的空隙中加入少量的空气(足以使饱和度降低1-2%)，才能显著提高液化强度，降低剪切波速。因此，通过空气包裹，新的或现有的场地可能会得到改善，以抵御液化，并通过剪切波速度测量，其充分性可以得到验证。这项研究有一些具体的目标，旨在提供对空气包裹砂的行为的初步了解，并确定未来需要进行的重要研究领域，以将这一概念提升为充分发展和实用的液化缓解措施。本研究的目的可以用问题的形式表述如下：1.如何在松散的饱和砂土中引入空气？2.如何制备不同饱和度(从95%到100%)的样品？3.如何准确地测量饱和度(最高可达0.1%)？4.空气捕获将如何影响液化强度？5.空气的存在对土壤的其他性质有何影响？6.砂的粒度分布和角度对上述结果有何影响？7.空气可以被困在下面多久不同的流动梯度？这项研究将对开发具有成本效益的液化缓解措施做出重大贡献。它还将对提高减少地震给社区造成的预期损失的能力产生更广泛的影响。这项研究将利用地质环境领域的专业知识，利用空气注入进行补救。