U.S.-Egypt Cooperative Research: Modeling and Analysis of Geogrid-Reinforced Earth Structures under Earthquake Loading

0514108 AshmawyDescription：该项目支持南佛罗里达大学(USF)土木工程系Alaa Ashmawy博士和开罗国家研究中心(NRC)Ahmed Abdelrahman博士的合作研究。他们计划研究地震荷载下土工格栅加筋土结构的建模和分析。智力优势：机械稳定土(MSE)墙对地震荷载的机械反应尚不完全清楚。尽管MSE结构在地震荷载作用下表现出良好的整体稳定性，但其变形和破坏行为以及内应力状态的变化还没有得到广泛的研究。PI设计了一种新的多功能土工合成材料测试仪，可以对多种土工格栅系统进行拉拔和剪切测试。该仪器目前安置在埃及的NRC，将用于研究颗粒土壤和土工格栅包裹体之间的循环相互作用。埃及的合作者将进行一项实验计划，以检查土-夹杂物界面的循环应力-变形特征与加筋刚度和夹杂物几何形状的关系。将在现有设备上增加一个伺服控制系统，以增强其测试能力。该系统将在USF使用有限元/有限差分软件进行数值建模，以验证和校准实验数据。将对现行的加筋土设计和土工格栅制造标准进行相应的修改。本文的研究工作将填补加筋土体系在循环或动力荷载作用下应力-变形特性研究领域的空白。开罗核管理委员会将提供实验研究所需的基础设施。软件和数字工具可以同时在美国联邦获得。这些发现对MSE墙在地震荷载下的修复和长期维护具有重要意义。广泛的影响：埃及合作者的杰出资质和他的机构提供的支持将确保开发高质量的实验数据用于分析。一名高素质的美国研究生已被国际和平研究所确定并招募参与研究，并将于2005年夏天开始研究生学习。她将参观埃及的研究所和实验室。研究成果的广泛传播将通过在期刊、会议记录和互联网上发表来确保。该项目得到了美国-埃及联合基金计划的支持，该计划为两国的科学家和工程师提供资助，以开展这些合作活动。

0514108AshmawyDescription: This project supports collaborative research by Dr. Alaa Ashmawy, Department of Civil Engineering, University of South Florida (USF), Tampa, Florida and Dr. Ahmed Abdelrahman, National Research Center (NRC), Cairo. They plan to study the modeling and analysis of geogrid-reinforced earth structure under earthquake loading. Intellectual merit: The mechanical response of Mechanically Stabilized Earth (MSE) walls to earthquake loading is not fully understood. While MSE structures perform well in terms of overall stability during earthquake loading, the deformation and distress behavior, as well as the change in internal stress state, have not been widely investigated. The PI has designed a new multi-purpose geosynthetic testing apparatus capable of performing pullout and shear testing on a wide range of soil-geogrid systems. The apparatus, currently housed at the NRC in Egypt, is to be utilized to investigate the cyclic interaction between granular soils and geogrid inclusions. An experimental program will be carried out by the Egyptian collaborators to examine the cyclic stress-deformation characteristics of soil-inclusion interfaces in relation to reinforcement stiffness and inclusion geometry. A servo-control system will be added to the existing equipment to enhance its testing capabilities. Numerical modeling of the system will be conducted at the USF using finite element/finite difference software to verify and calibrate the experimental data. Modifications to the current reinforced earth design and geogrid manufacturing standards will be proposed accordingly. The proposed research activities will fill in a gap in the area of stress-deformation characteristics of reinforced soil system under cyclic or dynamic loading. The NRC Cairo will provide the infrastructure needed for the experimental study. The software and numerical tools are, in parallel, available at the USF. The findings can have significant implications to the repair and long-term maintenance of MSE walls subjected to earthquake loading.Broader Impacts: The outstanding qualifications of the Egyptian collaborator and the support provided by his institution will ensure the development of high quality experimental data for analysis. A highly qualified American graduate student has already been identified and recruited by the PI to participate in the research and will commence her graduate studies in Summer 2005. She will visit the Egyptian institution and labs. Broad dissemination of research findings will be secured through publication in journals, conference proceedings, and the Internet. This project is being supported under the US-Egypt Joint Fund Program, which provides grants to scientists and engineers in both countries to carry out these cooperative activities.