influence of transverse and longitudinal members of coated polyester-yarn geogrid on pullout response under low normal stress

This paper presents an experimental investigation of the effectiveness of longitudinal and transverse members of bitumen-coated polyester-yarn geogrids under low normal stress using large-scale pullout apparatus. the tests first compare the pullout behavior of a geosynthetic sheet with that of the geogrid. it then compares the pullout behavior of geogrids with different spacing of longitudinal and transverse members. the results show that under low normal stresses, the behavior of the sheet and the geogrid is comparable. the spacing between transverse ribs displays very little influence on peak pullout resistance of the geogrids under low normal stress. increase in spacing between longitudinal ribs reduces the interaction between them. as a result, after the critical spacing of 70 mm determined for present test conditions, the total pullout resistance of the geogrid specimens is the product of the pullout resistance per rib with the number of longitudinal ribs in the respective specimens.