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

饱和土体由固相和流体两相组成。单个固体颗粒形成了一个可变形的固体骨架，其中相互连接的毛孔充满了流体。饱和土体在剪切波作用下，两相之间的相对运动对饱和土体的动力特性有两方面的影响：孔隙流体诱导的减振(即耗能)和有效土体密度。有效土密度与剪切波传播过程中随固体骨架运动的孔隙流体的比例有关，且总是小于或等于饱和密度。由于已发表的文献缺乏对这两种影响的定量评估，在目前的岩土工程研究和实践中普遍忽视了这两种影响。然而，最近的研究表明，这两种效应对于高渗透性的土壤(例如砂土和砾石)和/或在高频激励下是重要的。本研究的目的是对饱和土中孔隙流体诱发的阻尼和有效密度提供基本的认识、定量的评估和实用的解决方案。这项研究主要是由于涉及高频横波的岩土实验室和现场测试(例如离心机、弯曲元件、地震CPT)的广泛传播和日益流行。本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，将基于同时考虑毕奥流动和喷射流动的框架，推导出孔隙流体诱导的阻尼和有效密度的解析解。拟议的实验测试将使用共振柱测试来验证分析工作，并检查剪切应变和样品尺寸的影响。这项研究将通过开发易于研究人员和实践者使用的解决方案来弥合理论和实践之间的差距。它有可能改变研究人员和工程师解释数据和执行与土壤动力学和岩土地震工程有关的分析的方式。归根结底，好处将是减少地震给社会造成的损失。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，以便对本科生和研究生进行研究和教育。这项研究项目将促进这一努力，并激发学生？对这个职业的兴趣。

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.