US-Egypt Cooperative Research: Physical and Numerical Modeling of Geogrid-Soil Cyclic Interaction

0310183 AshmawyDescription：该奖项支持南佛罗里达大学(USF)土木工程系Alaa Ashmawy博士和埃及开罗国家研究中心(NRC)土木工程系Ahmed Abdel-Rahman博士的联合研究项目。他们建议研究土工格栅-土壤循环相互作用的物理和数值模拟。在美国和埃及，土工格栅作为机械夹层在土方施工中的使用都在增加。然而，颗粒土与土工格栅之间的相互作用机理尚不完全清楚，特别是在交通和地震等循环荷载条件下。在早期的一个项目中，主要研究人员设计和制造了一种新的多功能土工合成材料测试仪，能够对土-土工格栅界面进行拉拔和直剪试验。PIS计划利用目前安装在开罗NRC的新设备来研究颗粒土壤和土工格栅包裹体之间的循环相互作用。埃及团队将进行一项全面的实验计划，以检查土工格栅的静态和循环拔出强度与土工格栅开口尺寸和颗粒尺寸的关系。USF的团队将使用离散元方法(DEM)对系统的微观力学进行数值建模，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。范围：PI最近开发了一种使用DEM方法对角粒子进行数值建模的新技术。这项计划中的研究活动将通过与埃及团队收集的实验数据进行比较，对该技术进行验证和改进。开罗的国家研究中心拥有实验研究所需的基础设施，美国联邦也提供了数字高程模型软件、算法和数值研究工具。这些发现有望推进关于土工合成材料-土壤相互作用以及加筋颗粒土系统的离散单元建模的知识状况。该项目将涉及一名美国研究生，她将通过访问合作科学家在开罗的实验室并在其工作中获得独特的学习机会。参与该项目的本科生也将通过美国联邦工程学院的REU项目得到支持。这两名学生都是代表不足的群体的成员。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。

0310183AshmawyDescription: This award supports a joint research project between Dr. Alaa Ashmawy, Department of Civil and Environmental Engineering, University of South Florida (USF), Tampa, Florida and Dr. Ahmed Abdel-Rahman, Civil Engineering Department, the National Research Center (NRC), Cairo, Egypt. They propose to investigate the physical and numerical modeling of geogrid-soil cyclic interaction. The use of geogrids as mechanical inclusions in earth construction has been on the rise in both the US and Egypt. However, the interaction mechanisms between granular soils and geogrids are not yet fully understood, especially under cyclic loading conditions such as traffic and earthquake loading. In an earlier project, the principal investigators designed and manufactured a new multi-purpose geosynthetic testing apparatus capable of performing pullout and direct shear testing on soil-geogrid interfaces. The PIs plan to utilize the new apparatus, currently housed at the NRC in Cairo, to investigate the cyclic interaction between granular soils and geogrid inclusions. The Egyptian team will carry out a comprehensive experimental program to examine the dependence of static and cyclic pullout strength on geogrid opening dimensions in relation to grain size. The team at USF will conduct numerical modeling of the micromechanics of the system using the Discrete Element Method (DEM) to verify and calibrate the experimental data. Modifications to the current reinforced earth design and geogrid manufacturing standards will be proposed accordingly. Scope: The PI has recently developed a new technique for numerical modeling of angular particles using the DEM method. This planned research activity will allow validation and improvement of the technique through comparison with experimental data collected by the Egyptian team. The NRC in Cairo possesses the necessary infrastructure for the experimental study, and the DEM software, algorithms, and numerical research tools are available at the USF. The findings are expected to advance the state of knowledge with respect to geosynthetic-soil interaction as well as discrete element modeling of reinforced granular soil systems. The project will involve an American graduate student who will have a unique learning opportunity through her visit to and work at the cooperating scientist's laboratory in Cairo. An undergraduate student working on the project will also be supported through a REU program at the USF's College of Engineering. Both students are members of underrepresented groups. Broad dissemination of research findings will be done through publication in journals, conference proceedings, and the Internet.