Characterization of soil behaviour for earthquake engineering applications

地震工程应用中的土壤行为表征

• 批准号: RGPIN-2018-05334
• 负责人: Sivathayalan, Siva
• 金额: $ 3.79万
• 依托单位: Carleton University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=749112
• 关键词: Characterization; soil; behaviour; earthquake; engineering

Current seismic design approach is generally conservative as it relies primarily on empirical data to assess the liquefaction hazard. As a result, attempts to safeguard against possible lifeline failures during earthquakes often result in huge economic costs. Better understanding of the behavior of soils under actual in-situ loading paths and drainage conditions is essential to properly characterize the response of soils during earthquakes. It will enable the formulation of comprehensive models that will lead to reliable predictions of the response of the geotechnical structures under imposed loads.Fundamental understanding of soil behavior has mainly been derived from laboratory tests under fully drained or fully undrained conditions along specific stress paths. In reality, in-situ stress paths would be dictated by variations in all three principal stresses, and deformation would invariably involve simultaneous changes in pore-volume and pore-pressure. While drained and undrained approximations might yield sufficient accuracy under specific situations, there are several instances during which such approximations will not yield satisfactory results. Insights into the liquefaction phenomena have generally been elicited by simulating the propagation of body waves (often a vertically propagating s-wave). But, a large number of liquefaction failures occur due to surface-wave loading. At present virtually nothing is known about whether current understanding applies to liquefaction due to surface waves (e.g., Rayleigh wave) or combined body waves (simultaneous p- and s-waves). The proposed research is the first ever attempt to simulate the stress conditions due to Rayleigh (or simultaneous p- and s-) waves using a hollow cylinder torsional shear (HCT) device. This is a completely new line of inquiry in experimental research and our laboratory is one of the very few in the world that can explore the response of soils along such complex stress paths.Proposed research on the effects of 3D loading paths on Leda clay also contains several novel and innovative elements. The new HCT sample trimmer will allow using a given high-quality undisturbed Leda clay specimen (obtained using the Laval sampler) for one HCT test, and up to 12 triaxial or 8 simple shear tests (or a combination of the two). This is the first such attempt ever where an HCT specimen is prepared while preserving the inner core for triaxial and/or simple shear tests.Improved understanding of the effects of environmental factors on soil behavior is essential to pursue resource development in the north, and to address concerns related to global warming and sustainable development. Site characterization methods that consider simultaneous changes in pore volume and pressure will yield more meaningful results. The outcome of the proposed research will directly contribute to the safety of infrastructure, mine tailings and hydro dams.

当前的地震设计方法通常是保守的，因为它主要依赖于经验数据来评估液化危险。结果，试图保护地震期间可能的生命线失败通常会导致巨大的经济成本。更好地了解土壤在实际的原位载荷路径和排水条件下的行为，对于正确表征地震期间土壤的反应至关重要。它将实现综合模型的制定，从而使岩土结构在施加的载荷下的响应进行可靠的预测。对土壤行为的汇款理解主要是在沿特定应力路径的完全排水或完全不排水条件下的实验室测试得出的。实际上，原位应力路径将取决于所有三种主要应力的变化，并且变形总是涉及孔隙体积和孔隙压力的同时变化。尽管在特定情况下排干和未排水的近似可能会产生足够的精度，但在某些情况下，这种近似值不会产生令人满意的结果。通常通过模拟体波的传播（通常是垂直传播的S波）来引起对液化现象的见解。但是，由于地表波的负载，发生了大量的液化故障。目前，几乎尚不了解当前的理解是否适用于由于表面波（例如瑞利波）或联合体波（同时的P-和S波）引起的液化。拟议的研究是有史以来第一次尝试使用空心缸扭转剪切设备（HCT）设备来模拟由于雷利（或同时的P-和S-）波引起的应力条件的尝试。这是实验研究中的全新询问线，我们的实验室是世界上少数几个可以探索沿这种复杂应力路径的土壤反应的少数人之一。关于3D载荷路径对Leda Clay的影响的研究还包含了几种新颖和创新的元素。新的HCT样品修剪器将允许使用给定的高质量的不受干扰的Leda粘土标本（使用Laval采样器获得）进行一次HCT测试，并最多12个三轴或8个简单的剪切测试（或两者的组合）。这是有史以来第一次制备HCT标本的尝试，同时保留了三轴和/或简单剪切测试的内部核心。对环境因素对土壤行为的影响的理解对于追求北部的资源发展至关重要，并解决与全球变暖和可持续发展和可持续发展有关的问题。考虑同时改变孔隙体积和压力的位点表征方法将产生更有意义的结果。拟议的研究的结果将直接有助于基础设施，矿山尾矿和水坝的安全。