Assessment of junction strength of geogrids by a multi-junction test method

Abstract

The aperture structure of a geogrid exhibits a significant mutual effect with the surrounding soil, and this characteristic allows the geogrid to be used as a prime reinforcement for earth structures. This mutual effect between geogrid and the surrounding soil can be explained by the friction between the soil and the geogrid surface and the passive resistance of the cross direction ribs of the geogrid’s aperture structure. The load induced by friction and the passive resistance of the cross direction rib is transferred to the geogrid’s machine direction rib via the junction to accommodate the load of the soil. Therefore, the junction of the geogrid should have sufficient strength for the load transfer, and the assessment of this strength should be accurate. The most widely used junction strength test method is GRI GG-2, which only tests for a single junction. The GRI GG-2 test method has an inherent weakness in not being able to take into account the scale effect of geogrid specimens. Most of the geosynthetics being used for civil engineering are used as tensile members, and they are subject to an assessment of their tensile strength by taking a specimen of wide width. Thus, it follows that a multi-junction strength test method is the most appropriate for assessing the junction strength of geogrid, when considering the scale effect. This study proposes a multi-junction test method for the assessment of a geogrid’s junction strength, and the results of this proposed test are analyzed and compared with those of the single-junction test.