Volume 23, Issue 2 (June 2000)
Elastic Modulus of Geogrid-Reinforced Sand Using Plate Load Tests
An experimental study was conducted to evaluate the elastic modulus of sand reinforced with polymeric geogrids. A total of nine plate load tests were performed in the laboratory using a 1.52 m × 1.52 m × 1.37 m (length × width × depth) test box, and a 0.3 m square test plate. The measured test data were used to evaluate a modulus constant (E1), rather than the bearing capacity, as traditionally presented in literature. The modulus constant was estimated based on two deformation levels of 9.2 mm and 4.6 mm. These deformation levels, defined as δ1 and δ0.5, correspond to normalized settlement ratios (δ/B) of 1.5 and 3.0%, respectively, where B = width of the test plate. In general, a stiffer load-settlement response was measured when the geogrid reinforcement was included. Using SR1 geogrids with sand, the modulus constant (E1) decreased as a function of increasing u/B ratio (u = distance from plate to Eop reinforcement layer). In comparison, results indicated the presence of a critical u/B ratio when the SR2 geogrids were used. In this study, this particular ratio was estimated to be 0.65. Values of E1 from large scale model testing by Adams and Collin (1997) correlated well with E1 values evaluated from this testing program.