Development of a Soil-Specific Liquefaction Assessment Framework: Role of Soil Gradation

土壤特定液化评估框架的开发：土壤级配的作用

• 批准号: RGPIN-2016-05622
• 负责人: Ghafghazi, Mohsen
• 金额: $ 1.68万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=709784
• 关键词: Development; Soil; Specific; Liquefaction; Assessment

Assessment of liquefaction susceptibility and its consequences is a major part of geotechnical earthquake engineering. The practice relies on a case-history-based relation between in-situ penetration tests and cyclic response of soils. Apart from a poorly understood fines content correction, soils with different compositions and gradations and widely varied mechanical properties are essentially viewed as uniformly graded quartz sand. The existing methods would not have predicted liquefaction in almost any of the sites where liquefaction of widely graded gravelly soils resulted in widespread damage during the 2008 Wenchuan, China earthquake. Soil gradation has a first order effect on dilatancy and compressibility, as well as particle breakage; factors that control the penetration resistance and cyclic response of soils in different ways. Previous research suggests that wider gradation has a marginal effect on cyclic resistance, but imposes a more pronounced increase on penetration resistance. Consequently, widely graded soils with similar penetration resistance to uniform sands can have a significantly weaker cyclic response. The short-term goal of the research program is to develop a mechanistic framework that explains the general effects of gradation on the cyclic response of cohesionless soils and the penetration resistance used for its in-situ evaluation. The work will provide a scientific explanation of the existing fines content correction, and expand the concept to incorporate all widely graded soils including those with significant gravel content. The long-term goal is developing practical, well-validated, soil-specific liquefaction criteria that take into account independently measurable soil properties. Four specific components aim at (i) quantifying the influence of gradation on dilatancy, compressibility, particle breakage, and cyclic response, (ii) quantifying the influence of field vs. laboratory soil fabric on behaviour, (iii) modelling the Cone Penetration Test and investigating the influence of gradation on its measurements and (iv) developing general gradation corrections for the case-history-based method and validation. By integrating the influence of soil properties into the current liquefaction assessment practice, the research will reduce the significant uncertainty in dealing with soils that deviate from the idealised uniform sand case. Large economic gains can be realised where current conservatism prompts unnecessary remedial work, and risk will be reduced by identifying unrecognised liquefaction hazard. The research program will create an interactive environment where undergraduate, master's and PhD students performing advanced laboratory tests and innovative numerical analyses will collaborate with each other, and with leading national and international experts from both industry and academia.

评估液化易感性及其后果是岩土技术工程的主要组成部分。该做法依赖于原位渗透测试与土壤环反应之间的基于病例历史的关系。除了详尽的罚款含量校正外，具有不同组成和渐变以及广泛不同机械性能的土壤基本上被视为均匀分级的石英砂。现有的方法不会预测几乎所有地点的液化，在这些地点中，液化广泛的碎石土壤会在2008年中国地震中造成广泛损害。 土壤等级对膨胀和可压缩性以及颗粒破裂具有一阶效应。以不同方式控制土壤的抗渗透性和循环反应的因素。先前的研究表明，较宽的渐变对循环抗性具有边缘作用，但对穿透性抗性的增加更为明显。因此，对均匀沙子具有相似抗渗透性的广泛分级土壤可能具有明显较弱的环状反应。 该研究计划的短期目标是开发一个机械框架，该框架解释了渐变对无内聚土壤循环反应的一般影响以及用于其原地评估的渗透性抗性。这项工作将对现有罚款内容进行校正提供科学的解释，并扩大概念，以结合所有广泛的土壤，包括那些具有重要砾石含量的土壤。长期的目标是制定实用，验证，土壤特异性液化标准，这些标准考虑到可独立测量的土壤特性。 四个特定组成部分旨在（i）量化渐变对膨胀，可压缩性，颗粒断裂和环状响应的影响，（ii）量化田间与实验室土壤织物对行为的影响，（III）对锥体穿透性测试进行建模并研究等级对其测量和（IV）的影响，并（IV）对基于病例校正进行基于病例校正的方法和验证方法。 通过将土壤特性的影响整合到当前的液化评估实践中，该研究将减少应对偏离理想化均匀砂盒的土壤的重大不确定性。可以在当前的保守主义促使不必要的补救工作的情况下实现巨大的经济收益，并且通过识别未识别的液化危害将降低风险。 该研究计划将创建一个互动环境，在该环境中，本科生，硕士和博士生进行高级实验室测试和创新的数值分析将相互合作，并与来自行业和学术界的领先的国家和国际专家进行合作。