Experimental and PIV evaluation of grain size and distribution on soil-geogrid interactions in pullout test

Due to complexity and a variety of influential factors, interactions at the soil-reinforcement interface are still not fully understood. In current research, pullout tests are conducted to evaluate the grain size and distribution effects on interactions at the soil-geogrid interface and particle displacements during pullout. Large scale pullout tests (i.e. 100 × 60 × 60 cm) were carried out using three granular soils with different grain size and distributions reinforced with an HDPE geogrid subjected to σn = 25, 50 and 100 kPa. Digital images were captured during tests and processed using particle image velocimetry (PIV) together with three dimensional finite element analysis using ABAQUS. The results showed that the pullout forces and the shear zone thickness substantially increase with increase in grain size, that particles close to the ribs displace in a circular manner and that strain distributions become more symmetrical. The results of finite element analysis also showed close agreement with the test results.