SGER: Air Entrapment for Liquefaction Mitigation

0234365，Mishac Yegian，东北大学“液化缓解的空气夹带“这一行动是为了支持减轻土壤液化的创新方法的科学和技术可行性研究。液化引起的建筑环境破坏可能是灾难性的。 在过去的四十年里，人们已经做出了大量的努力来了解液化的机制，并开发程序来分析在给定的地震事件期间在一个网站的液化潜力。 虽然对液化的研究仍在继续，但岩土工程实践已开发出各种场地改善技术，可以减轻液化的潜在影响。 这种缓解措施费用昂贵，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。其概念是在饱和砂存款中引入空气，以增加其抗液化能力。 实验室和现场经验表明，只有少量的空气在孔隙中，否则完全饱和的沙子（足以减少1至2%的饱和度）可以显着增加液化强度，并降低剪切波速度。 因此，通过空气截留，一个新的或现有的网站可以潜在地改善，以抵抗液化，并通过剪切波速度测量，其充分性可以得到验证。该研究有一些具体的目标，旨在提供一个初步了解空气截留砂的行为，以及确定未来研究的重要领域，这些领域将需要将概念推进到充分发展和实际的液化缓解措施。 本研究的目的可以用问题的形式表述如下：1.如何将空气引入松散的饱和砂土中？2.如何制备不同饱和度（95 - 100%）的样品？3.如何准确测量饱和度（最高可达0.1%）？4.夹气对液化强度有何影响？5.空气的存在如何影响土壤的其他性质？6.砂的粒度分布和棱角性如何影响上述结果？7.在不同的流动梯度下，空气能滞留多长时间？这项研究将是一个重大贡献的发展具有成本效益的液化缓解措施。 它还将对提高减少地震对社区的预期损失的能力产生更广泛的影响。 该研究将利用地质环境领域的专门知识，使用空气注入进行补救。

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.