Analytical and Experimental Study of Pore Fluid Induced Damping and Effective Density in Saturated Soil During Shear Wave Excitations

剪切波激励下饱和土孔隙流体诱导阻尼和有效密度的分析与实验研究

• 批准号: 1059588
• 负责人: Tong Qiu
• 金额: $ 6万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1059588&HistoricalAwards=false
• 关键词: Analytical; Experimental; Study; Pore; Fluid

Saturated soil consists of a solid phase and a fluid phase. Individual solid grains form a deformable solid skeleton with interconnected pores filled with fluids. When saturated soil undergoes shear wave excitations, the relative motion between the two phases has two effects on the dynamic behavior of saturated soil: pore fluid induced damping (i.e., energy dissipation) and effective soil density. The effective soil density is related to the fraction of pore fluid that moves with the solid skeleton during shear wave propagation, and is always smaller or equal to the saturated density. Due to a lack of quantitative assessment of these two effects in published literature, they are generally neglected in current geotechnical engineering research and practice. However, recent research indicates that these two effects are important for soils with high permeability (e.g., sands and gravels) and/or under high-frequency excitations. The objective of this research is to provide fundamental understanding, quantitative assessment, and practical solutions to pore fluid induced damping and effective density in saturated soil. This research is primarily motivated by the wide spread and increasing popularity of geotechnical laboratory and field tests involving high-frequency shear waves (e.g., centrifuge, bender elements, seismic CPT). The objective of this research will be achieved through analytical study and experimental testing. In the proposed analytical study, analytical solutions of pore fluid induced damping and effective density will be derived based on a framework that considers both Biot flow and squirt flow. The proposed experimental testing will use resonant column tests to provide validation of the analytical work and examine the effects of shear strain and specimen size. This research will serve to bridge the gap between theory and practice by developing solutions that can be easily used by researchers and practitioners. It has the potential to transform the way in which researchers and engineers interpret data and perform analyses relating to soil dynamics and geotechnical earthquake engineering. Ultimately, the benefits will be the reduction of losses to society as a result of earthquakes. Broader impacts also include improving educational opportunities in the area of geotechnical engineering at Clarkson University. A soil dynamics testing laboratory is currently being developed to conduct research and educate students at both the undergraduate and graduate levels. This research project will foster that effort and spark students? interest in this profession.

饱和土壤由固相和流体相组成。 单个固体颗粒形成可变形的固体骨架，并带有互连的毛孔，充满了流体。 当饱和的土壤经历剪切波激发时，两个阶段之间的相对运动对饱和土壤的动态行为有两种影响：孔隙流体诱导的阻尼（即能量耗散）和有效的土壤密度。 有效的土壤密度与剪切波传播过程中用固体骨骼移动的孔流体的比例有关，并且始终较小或等于饱和密度。 由于缺乏对已发表文献中这两种影响的定量评估，因此在当前的岩土工程研究和实践中通常会忽略它们。 但是，最近的研究表明，这两种作用对于具有高渗透性（例如沙子和砾石）和/或高频激发的土壤很重要。 这项研究的目的是提供基本的理解，定量评估和实用解决方案，以使孔流体诱导的阻尼和饱和土壤中的有效密度。 这项研究主要是由涉及高频剪切波的岩土技术实验室和现场测试的广泛传播和日益普及（例如离心机，弯曲器元素，地震CPT）。 这项研究的目的将通过分析研究和实验测试来实现。 在拟议的分析研究中，将根据考虑Biot流量和喷气流量的框架来得出孔隙流体诱导的阻尼和有效密度的分析溶液。 提出的实验测试将使用谐振柱测试来提供分析工作的验证，并检查剪切应变和试样大小的影响。 这项研究将通过开发研究人员和从业者可以轻松使用的解决方案来弥合理论与实践之间的差距。 它有可能改变研究人员和工程师解释数据并进行与土壤动态和岩土技术地震工程有关的分析的方式。 最终，收益将是地震导致社会损失的减少。 更广泛的影响还包括改善克拉克森大学岩土工程领域的教育机会。 目前正在开发一个土壤动力学测试实验室，以在本科和研究生水平上进行研究和教育。 这个研究项目会促进这项努力并激发学生吗？对这个职业的兴趣。