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

该快速反应研究基金(RAPID)项目的总体目标是评估在相对细粒土壤中使用土壤液化缓解技术的潜力。这项技术利用了生物修复领域的新进展，将在俄勒冈州波特兰的一个现场进行现场测试。该项目解决了俄勒冈州的一个主要地震问题，那里的许多基础设施都建立在非塑性到低塑性的粉土上，在卡斯卡迪亚俯冲带9级地震中，这些粉土很容易液化。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是在这里处理的。CEI枢纽燃料箱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。如果本项目中的缓解方法在现场被证明是有效的，将为在可液化粉质土上的基础设施采用该解决方案提供垂直步骤。这将增强俄勒冈州在大地震后的弹性，并可在其他具有类似地下条件的地方采用。该项目将评估通过异化减少氮(反硝化)来减轻相对细粒土壤的液化潜力的微生物诱导去饱和的可能性。我们假设1)经过两周处理的反硝化作用可以将田间粉质土壤的饱和度降低到80%，2)这种程度的去饱和将消除在原位循环应变下处理的土壤中孔压的产生，以及3)由于粉质土壤中的小孔隙尺寸，去饱和将持续数年(尽管这一点还需要在后续的研究中得到验证)。我们评估这些假设的方法包括在治疗前后在现场使用NHERI@UTexas现场设备进行现场震动，并在接下来的3到5年内定期监测压缩(P-)波的速度。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.