Pull-out testing facility for geosynthetics.

PDFTech ReportFHWA/LA-92/24087-1GTGeosyntheticsReinforcement (Engineering)Soil structureGeogridsDirect shear testsTestingLouisianaLouisiana State University, Baton RougeFarrag, KhalidJuran, IlanAcar, Y. B.Louisiana State University (Baton Rouge, La.). Dept. of Civil and Environmental EngineeringLouisiana Transportation Research CenterUnited States. Federal Highway AdministrationUS Transportation CollectionThe considerable increase in using geosynthetics in soil reinforcement made it necessary to develop methods of measuring the interaction properties and modeling load transfer in reinforced-soil structures. The large number of factors that influence the interaction mechanism makes it difficult to standardize the equipment design, testing methodology and data interpretation procedure. The factors are mainly related to the equipment boundary effects, testing conditions, and soil and geosynthetics properties.In order to develop a methodology for evaluating the interface properties of geogrids, a pull-out box and a direct shear box are constructed and instrumented. A testing program is conducted to evaluate the performance of the facility and the effect of different testing parameters (a.g. specimen dimensions, soil thickness, box boundary effects, pull-out rate, soil compaction and relative density, and confining pressure) on the pull-out interaction mechanism of geogrids. Standard equipment design and testing procedure are recommended to overcome most of the limitation in the current practice.A data analysis procedure is established to determine the interface properties and the confined reinforcement characteristics from pull-out test results. The data analysis incorporates the effect of reinforcement extensibility on the soil-geogrid interface mechanism. The interface parameters are evaluated through comparison with the results from tests performed in the large direct shear box