Preliminary Evaluation of Colloidal Silica Transport Mechanisms for Passive Site Remediation of Liquefiable Soils

CMS-0219987，Patricia M. Gallagher，Drexel大学“液化土壤被动场地稳定的胶体二氧化硅运输机制的初步评估“该项目涉及胶体二氧化硅运输机制的探索性评估，以稳定液化土壤的形成。 研究结果将用于支持开发一种非破坏性的地基加固技术。 “被动场地补救”是一个新概念，用于在易受液化影响的已开发场地非破坏性地减轻液化风险。 该概念是在场地的上坡边缘缓慢注入稳定材料，并利用地下水流将稳定剂输送到可液化区域。重点是将胶体二氧化硅溶液均匀地输送到可液化土壤沉积物中，随后胶凝化以减轻液化敏感性。 研究的主要目的是：（1）确定是否可以通过一个可液化土壤柱输送胶态二氧化硅灌浆，以足够的浓度来稳定砂;（2）确定灌浆是否会在输送后沿整个柱的长度沿着凝胶化;（3）了解胶态二氧化硅通过可液化砂输送的机制。 该研究涉及实验室实验，包括短柱和长柱试验，以确定影响胶体二氧化硅灌浆在可液化土壤中运输的变量。 要考虑的参数包括被认为对灌浆输送影响最大的地球化学和物理因素，如pH值、灌浆溶液的离子强度、流速和砂层的孔径。 还将考虑对可变密度和可变粘度的胶凝液输送的影响。 这项研究将为未来被动场地修复的实施技术和现场测试的发展奠定基础。 研究成果将在岩土地震工程、地基加固、灌浆和环境修复领域的研究人员和从业人员中广泛传播。被动场地修复技术可能广泛应用于易受液化影响的已开发场地，传统的地基加固方法难以或不可能实施。 这些技术也可应用于地下污染难以补救的城市地区。

CMS-0219987, Patricia M. Gallagher, Drexel University"Preliminary Evaluation of Colloidal Silica Transport Mechanisms for Passive Site Stabilization of Liquefiable Soils"This project involves an exploratory evaluation of colloidal silica transport mechanisms to stabilize liquefiable soil formations. The results will be used to support development of a non-disruptive technique for ground improvement. "Passive site remediation" is a new concept for non-disruptive mitigation of liquefaction risk at developed sites susceptible to liquefaction. The concept is to slowly inject a stabilizing material at the up-gradient edge of a site, and deliver the stabilizer to the liquefiable area using the groundwater flow.The focus is on the ability to deliver colloidal silica solutions uniformly into liquefiable soil deposits, with subsequent gelation to mitigate the liquefaction susceptibility. The main goals of the research are: (1) to determine if colloidal silica grout can be transported through a column of liquefiable soils in an adequate concentration to stabilize the sand; (2) to determine if the grout will gel along the entire length of the column after delivery; and (3) to understand the mechanisms of colloidal silica transport through liquefiable sands. The research involves laboratory experiments consisting of short and long column tests to identify the variables that influence colloidal silica grout transport in liquefiable soils. The parameters to be considered include the geochemical and physical factors thought to affect grout transport most strongly, such as pH, ionic strength of the grout solution, flow velocity, and pore size of the sand formation. The effects on the transport of gelling fluids with variable density and variable viscosity will also be considered. This research will set the stage for future development of implementation technologies and field testing of passive site remediation. The research results will be widely disseminated among researchers and practitioners in the areas of geotechnical earthquake engineering, ground improvement, grouting, and environmental remediation.Passive site remediation techniques could have broad application for developed sites susceptible to liquefaction, where traditional ground improvement methods are difficult or impossible to implement. These techniques could also have application to urban areas where subsurface contamination is difficult to remediate.