Field Application of Induced Partial Saturation (IPS) for Liquefaction Mitigation

地震对建筑物、桥梁、大坝和发电厂等建筑环境造成的灾难性影响，往往是由土壤液化引起的地面塌陷造成的。液化是指在地震期间饱和砂土对建筑物的支撑能力的丧失。可以用来防止液化发生的现有技术非常昂贵，而且只能在新的地点和现有的结构中实施。迫切需要开发一种具有成本效益和实用的液化预防技术，该技术可应用于新的场地以及现有结构位于可液化土壤上的场地。这项研究将探索提出一种称为诱导部分饱和(IPS)的创新概念，在该概念中，可液化砂子的水分饱和度降低，从而防止其在地震中破坏。诱导部分饱和是将产生气体的化学溶液注入可液化的砂土中，通过溶液的运输和反应，在砂土的孔隙中控制地产生氧气气泡，从而降低地下的含水饱和度。这个团队在东北大学进行的研究表明，沙子的部分饱和确实可以防止液化的发生。这项研究的结果将推动IPS作为一种技术上可行、实用和成本效益高的现场液化缓解技术。IPS将产生广泛影响，包括降低全球地震风险。此外，所获得的基本知识将大大有助于加强受污染地下水的修复和恢复技术，这是一个对人类健康有重大影响的重大问题。此外，这项研究将继续为初高中学生和教师创造独特的机会，参与研究人员地震工程实验室的活动，通过演示和动手制作和测试结构模型来促进科学和工程。研究成果将通过研究人员的网站发布和提供。这项研究的数据和结果将被上传到NSF支持的NHERI数据库。本研究的目标是调查和推进诱导部分饱和作为一种可行的现场液化缓解技术。为实现这一目标，将开展以下三项主要研究工作：1)评价IPS处理的液化敏感砂土的特性；2)发展数值模拟以模拟实际现场条件下的IPS过程；以及3)在东北大学戴德姆校区的试验台上进行现场试验的性能评价，以增进对IPS处理砂土的基本知识并验证所开发的数值模拟。这些研究任务将产生关于在实际现场条件下诱导部分饱和的新的基础知识，以及关于现场砂对IPS处理的行为的新的基础知识。这项研究还将创造机会，开发实施IPS的现场工具和方法，以及开发数值模拟软件，以确定IPS作为地震液化缓解措施的现场应用的设计概念和参数。

Catastrophic effects of earthquakes on our built environment including, buildings, bridges, dams, and power plants, are often caused by ground failures due to soil liquefaction. Liquefaction refers to the loss of bearing capacity of saturated sandy soils to support structures during earthquakes. Existing techniques that can be used to prevent occurrence of liquefaction are very costly and can only be implemented at new sites and only at existing structures. There is a critical need to develop a cost-effective and practical liquefaction prevention technology that can be applied to new sites as well as sites with existing structures resting on liquefiable soils. This research will explore advancing an innovative concept referred to Induced Partial Saturation (IPS) in which water saturation of a liquefiable sands is reduced, thus preventing its failure during earthquakes. Induced Partial Saturation involves injection of a gas generating chemical solution into the liquefiable sandy ground, leading to controlled generation of oxygen gas bubbles within the pores of the sand through transport and reactivity of the solution, thus reducing water saturation in the ground. Research conducted by this team at Northeastern University demonstrated that partial saturation of sands indeed prevents the occurrence of liquefaction. The outcome of this research will advance IPS as a technically feasible, practical, and cost-effective field technique for liquefaction mitigation. IPS will have broad impacts, including reducing earthquake risk worldwide. Also, the fundamental knowledge gained will have significant benefits in enhancing technologies for remediation and restoration of contaminated groundwater, a major problem with significant impacts on human health. Furthermore, this research will continue to create unique opportunities for middle and high school students and teachers to participate in activities in the researchers' earthquake engineering laboratory, promoting science and engineering through demonstrations and hands-on structural model creation and testing. The research outcomes will be published and made available through the researchers' website. The data and finding of this research will be uploaded to the NSF-supported NHERI Data Depot.The goal of this research is to investigate and advance Induced Partial Saturation as a feasible field technique for liquefaction mitigation. To achieve this goal, the following three primary research tasks will be conducted: 1) Evaluation of behavior of liquefaction susceptible field sands treated by IPS, 2) Development of numerical simulation to model the IPS process under real field conditions, and 3) Evaluation of the performance of field experiments at a testbed at the Dedham campus of Northeastern University to advance fundamental knowledge on IPS treated sands and to verify the developed numerical simulation. The research tasks will lead to new fundamental knowledge on inducing partial saturation under real field conditions, and on the behavior of field sands to IPS treatment. The research will also create opportunities to develop field tools and methods for implementation of IPS as well as numerical simulation software to determine design concepts and parameters for field application of IPS as an earthquake liquefaction mitigation measure.