A Theoretical Analysis of the Maximum Load Transferred to the Junctions of a Geogrid Confined in Granular Soil

It is well known that the bearing resistance against a geogrid’s transverse rib is transferred through the geogrid junction when the geogrid is embedded in soil and subjected to pullout or tensile loading. However, there is not an established technical approach that can be used by design engineers to estimate the load transferred to the geogrid junction confined in granular soil. In this paper, a theoretical analysis is performed to estimate the maximum load transferred to the geogrid junction. The results of the analysis are presented in mathematical expressions that can be easily used by design engineers to estimate the maximum geogrid junction load which will allow the proper specification of the required geogrid junction strength accordingly. Geogrid junction strength is determined by using either the Geosynthetics Research Institute (GRI) GG-2 test method or the ASTM International (ASTM) D 7737 test method. Currently, the required junction strength is typically specified as a percentage of the geogrid rib strength (i.e., junction efficiency). Typically, the required junction efficiency can range from 10 to 90% of the single rib strength. This paper provides insight into establishing a proper geogrid junction strength specification based on using a factor of safety and the estimated maximum geogrid junction load. The paper also presents a historical prospective with regard to the development of the geogrid junction strength test methods GRI GG-2 and ASTM D 7737-11.