Role of Spatial Variability in Liquefaction Consequence Severity

空间变异在液化后果严重性中的作用

• 批准号: 1931069
• 负责人: Armin Stuedlein
• 金额: $ 9.78万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-15 至 2021-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1931069&HistoricalAwards=false
• 关键词: Role; Spatial; Variability; Liquefaction; Consequence

Earthquake-induced liquefaction can occur when strong ground shaking causes saturated, loose sand and silt sediments to lose their strength and ability to support structures, such as buildings, bridges, and port and harbor infrastructure. Unfortunately, population centers are often founded above and within the kinds of sediments that are susceptible to soil liquefaction. The periodic earthquakes produced in seismically-active zones tend to lead to widespread damage that can affect housing, critical infrastructure, utility, and emergency service networks. For example, $15B of damage was attributed to soil liquefaction resulting from the 2010-11 Canterbury Earthquake Sequence in New Zealand. More than 25,000 homes experienced liquefaction-related damage in the Tohoku and Kanto districts in Japan. The breadth of damage and disruption to the residents of earthquake-prone areas pose significant economic consequences if the liquefaction hazard is not sufficiently explored and mitigated, impacting the ability of communities to recover from an earthquake event. This project aims to leverage the significant dataset gathered within the New Zealand Geotechnical Database (NZGD) to identify the role of spatial variability of liquefaction-susceptible soil deposits on the severity of liquefaction-induced consequences. An improved understanding of the liquefaction phenomenon and resulting consequences may be obtained by linking those detectable geomorphological signatures to the performance of existing liquefaction triggering and severity models and the actual responses observed during the 2010-11 Canterbury Earthquake Sequence. Sites identified in the NZGD that have a sufficient number of soil explorations to establish the vertical and horizontal inherent variability of liquefiable soil deposits will form the basis for this work. One doctoral student and one undergraduate research assistant will work on this project, under the supervision of the Principal Investigator and in collaboration with researchers from the University of Canterbury, New Zealand. The analytical procedures necessary for evaluating the inherent spatial variability of soils will be distilled into a broadly-, and freely-distributed user-friendly framework to spur greater application of random field methods to the evaluation of liquefiable soil sites. This study will address potential shortcomings in existing techniques to assess liquefaction severity by considering the geologic and geomorphological signature of potentially-liquefiable soils deduced from measures of soil spatial variability quantified using random field theory (RFT). Observations of post-earthquake liquefaction severity following the Canterbury Earthquake Sequence provide a ready source of observations by which to test whether or not knowledge of spatial variability can reduce the inaccuracy of liquefaction severity measures. Measures of soil autocorrelation and inherent variability will be directly quantified using cone penetration test data in the NZGD using rigorous statistical methods to improve our understanding of the range in vertical and horizontal measures of spatial variability of liquefaction susceptible soils. Furthermore, this work will evaluate the potential for correlation of quantified random field model parameters and geomorphologic controls to relative accuracy or inaccuracy in liquefaction severity measures. This work will lay the groundwork for future studies by significantly increasing the number of sites characterized within the RFT framework, particularly measures of horizontal variability, as well as train current and future earthquake engineering educators and students in RFT to promote awareness of this interpretational framework by teaming with the NSF-sponsored Geotechnical Extreme Events Reconnaissance Association.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.

当强烈的地面震动导致饱和、松散的沙子和淤泥沉积物失去其强度和支撑结构（如建筑物、桥梁和港口和港口基础设施）的能力时，可能发生地震诱导的液化。 不幸的是，人口中心往往位于易受土壤液化影响的沉积物之上和之内。 在地震活跃区产生的周期性地震往往会导致广泛的破坏，可能影响住房，关键基础设施，公用事业和紧急服务网络。例如，新西兰2010-11年坎特伯雷地震序列造成的土壤液化造成了150亿美元的损失。 在日本东北部和关东地区，有25 000多所房屋遭受了与反政府武装有关的破坏。 如果不充分探索和减轻液化危害，地震多发地区居民遭受的破坏和破坏范围之广会造成严重的经济后果，影响社区从地震事件中恢复的能力。 该项目旨在利用新西兰岩土工程数据库（NZGD）中收集的重要数据集，以确定易受剥蚀影响的土壤沉积物的空间变异性对剥蚀引起的后果的严重性的作用。 通过将这些可检测的地貌特征与现有液化触发和严重程度模型的性能以及2010-11年坎特伯雷地震序列期间观察到的实际反应联系起来，可以更好地了解液化现象及其后果。 在新西兰地质发展局中确定的、进行了足够数量的土壤勘探以确定可液化土壤沉积物的纵向和横向固有变异性的地点将构成这项工作的基础。 一名博士生和一名本科生研究助理将在首席研究员的监督下，与新西兰坎特伯雷大学的研究人员合作，从事这一项目。 评估土壤固有空间变异性所需的分析程序将被提炼成一个广泛和自由分布的用户友好的框架，以促进随机场方法在可液化土壤场地评估中的更大应用。本研究将解决现有技术的潜在缺陷，以评估液化的严重程度，考虑潜在的可液化土壤的地质和地貌特征推导出的土壤空间变异性的措施，使用随机场理论（RFT）。 坎特伯雷地震序列之后的震后液化严重性观测提供了一个现成的观测源，通过该观测源来测试空间变异性知识是否可以减少液化严重性测量的不准确性。 土壤自相关性和固有变异性的测量将使用NZGD中的静力触探试验数据进行直接量化，使用严格的统计方法，以提高我们对液化敏感土壤空间变异性的垂直和水平测量范围的理解。此外，这项工作将评估量化的随机场模型参数和地貌控制的相关性，相对准确性或不准确性的液化严重性措施的潜力。 这项工作将为今后的研究奠定基础，大大增加RFT框架内表征的场地数量，特别是水平变异性的测量，以及培训RFT中当前和未来的地震工程教育工作者和学生，通过与NSF合作，提高对这一解释框架的认识-该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的评估被认为值得支持。影响审查标准。

项目成果

Quasi-site-specific multivariate probability distribution model for sparse, incomplete, and three-dimensional spatially varying soil data

• DOI: 10.1080/17499518.2021.1971256
• 发表时间: 2021-09
• 期刊: Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards
• 作者: J. Ching;K. Phoon;Zhiyong Yang;A. Stuedlein