Cyclic Loading Behavior of Fine-Grained Soils

本研究项目的目标是建立一个基本框架，以理解和描述受循环和单调不排水荷载影响的“可液化”细粒土壤的行为——这是开发评估土壤液化潜力的可靠设计方法的必要步骤。“可液化”一词是指在地震荷载作用下易受严重强度损失影响的细粒土壤。实现这一目标的主要任务是在广泛的条件下对选择的低塑性泥沙和粘土进行全面的实验室研究，以建立一个基本框架。项目包括单调加载、循环加载、循环后单调加载以及大范围围应力和空隙比固结试验，研究不排水加载行为与初始状态、准稳态和稳态条件之间的相互关系。它还包括对样品制备方法，应力历史和加载路径（即三轴与扭转剪切）在大范围内的孔隙比和围应力的影响的调查。本研究的结果将填补在理解地震加载时细粒土的行为方面的重要空白。从而协助开发工程程序，以评估与细粒土壤地震荷载反应有关的潜在地震危害。教育计划教育计划的目标是使土木工程专业的学生具备良好的工程哲学，严格的工程基础和基础知识，并了解理论和判断的互补作用。教育计划包括几个细节，将加强现有课程的基本实力，从而有助于在土木和环境工程方面提供鼓舞人心的全面教育。它包括以下内容：在设计课程中，有一个实践专业人员协助建立设计项目，然后在课程结束时讨论替代设计；选择这些和其他新的课程项目来说明基础理论和工程判断在土木与环境工程实践中的互补作用；制作关于现场特征的钻探和取样程序的教学录像；在本科实验教学中引入计算机数据采集系统通过暑期就业和自主研究选修课程，让本科生参与研究项目；并在适当的课程中介绍最近的研究成果

9502530 Boulanger The objective of this research project is to develop a fundamental framework for understanding and describing the behavior of "liquefiable" fine-grained soils subjected to cyclic and monotonic undrained loading -- a necessary step in the development of reliable design methodologies for assessing liquefaction potential of soils. The term "liquefiable" is used to denote fine-grained soils that would be considered susceptible to severe strength loss during earthquake loading. The primary task towards achieving this objective is a comprehensive laboratory study of select low-plasticity silts and clays over the wide range of conditions necessary to establish a fundamental framework. The project includes monotonic loading, cyclic loading, post-cyclic monotonic loading, and consolidation tests over a wide range of confining stresses and void ratios to investigate the interrelationships between the undrained loading behavior and the conditions of initial state, quasi-steady state, and steady state. It also includes an investigation of the influence of sample preparation method, stress history, and loading path (i.e., triaxial versus torsional shear) over a wide range of void ratios and confining stresses The results of this study will fill a vital gap in the understanding of the behavior of fine-grained soils during earthquake loading, and thereby assist in the development of engineering procedures for assessing potential earthquake hazards related to the earthquake loading response of fine-grained soils. EDUCATION PLAN The objective of the education plan is to equip civil engineering students with a sound philosophy of engineering, a rigorous grounding in engineering basics and fundamentals, and an appreciation of the complementary roles of theory and judgment. The education plan covers several details which will enhance the basic strength of the existing curriculum, and thereby contribute to an inspiring, well-rounded education in civil and environmental engineering. It includes the following items: In design courses, have a practicing professional assist in setting up the design project, and then discuss alternative designs at the end of the course; select these and other new course projects to illustrate the complementary roles of fundamental theory and engineering judgment in the practice of civil and environmental engineering; develop an instructional video on drilling and sampling procedures for site characterization; introduce computer- based data-acquisition systems into the undergraduate laboratory curriculum; involve undergraduates in research projects via summer employment and independent research electives; and introduce results from recent research in appropriate courses ***