RAPID/Collaborative Research: Liquefaction Mitigation of Silts using MIDP and Field Testing with NHERI UTexas Large Mobile Shakers

快速反应研究（RAPID）项目的总体目标是评估相对细粒土壤中土壤液化缓解技术的潜力。这项技术采用了生物补救领域的新进展，并将在位于俄勒冈州波特兰的一个地点进行实地测试。该项目解决了俄勒冈州的一个主要地震问题，该州的许多基础设施都建立在非塑性到低塑性的淤泥上，这些淤泥在9级卡斯卡迪亚俯冲带地震中容易液化。选择进行研究的地点靠近位于波特兰西北部的关键能源基础设施（CEI）枢纽，俄勒冈州90%的液体燃料和波特兰机场的所有喷气燃料都在这里处理。CEI枢纽燃料罐的地震脆弱性是俄勒冈州在大地震后恢复能力和能源可靠性的关键障碍。如果该项目中的缓解方法在现场被证明是有效的，它将为在可液化粉土上建立的基础设施采用该解决方案提供一个垂直步骤。这将提高俄勒冈州在大地震后的恢复力，并可在具有类似地下条件的其他地方采用。该项目将评估微生物通过氮的异化还原（反硝化）引起的去饱和的潜力，以减轻相对细粒土壤的液化潜力。我们假设：1）通过两周的处理，反硝化作用可以将现场粉质土壤的饱和度降低到80%，2）这种去饱和程度将消除原位循环应变下处理土壤中的孔隙水压力产生，3）粉质土孔隙小，饱和度降低的现象将持续多年（这需要在后续研究中进行验证）。我们评估这些假设的方法包括在处理前后使用NHERI@UTexas现场设备在现场进行原位摇动，并在未来3至5年内定期监测压缩（P-）波速度。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

The overall objective of this Grant for Rapid Response Research (RAPID) project is to evaluate the potential for a soil liquefaction mitigation technique in relatively fine-grained soils. This technique uses new advancements in the field of bio-remediation and will be tested in the field at a site located in Portland, Oregon. The project addresses a major seismic problem in Oregon, where many infrastructure facilities are founded on non-plastic to low-plasticity silts that are susceptible to liquefaction in a Magnitude 9 Cascadia Subduction Zone earthquake. The site selected for study are near the Critical Energy Infrastructure (CEI) hub located in northwest Portland, where 90 percent of the Oregon's liquid fuel and all jet fuels for Portland's airport are handled. The seismic vulnerability of fuel tanks at the CEI hub is a critical impediment to Oregon's resilience and energy reliability in the wake of a major earthquake. If the mitigation method in this project is proved to be effective in the field, it will provide a vertical step for adopting this solution for infrastructure founded on liquefiable silty soils. This will enhance the resiliency of Oregon after a major earthquake, and it can be adopted in other places with similar subsurface conditions.This project will evaluate the potential for microbially induced desaturation via dissimilatory reduction of nitrogen (denitrification) to mitigate liquefaction potential in relatively fine-grained soils. We hypothesize that 1) denitrification via two weeks of treatment can lower the degree of saturation to 80 percent in silty soils in the field, 2) this level of desaturation will eliminate pore water pressure generation in treated soils subjected to in-situ cyclic strains, and 3) the desaturation will persist for years due to the small pore size in silty soils (although this will need to be verified in subsequent research). Our approach to evaluate these hypotheses involves in-situ shaking using NHERI@UTexas field equipment at a site before and after treatment, and periodic monitoring of compression (P-) wave velocities during the next 3 to 5 years.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.