Soil–Nail Pullout Interaction in Loose Fill Materials

A laboratory study was conducted to investigate the behavior of soil nails embedded in loosely compacted sandy fills. By varying the overburden pressure, the peak pullout force and the load–displacement behavior were determined by carrying out pullout tests in a displacement-rate controlled manner. The test results were compared to other published ones. The present results show that the pullout resistance can be interpreted with conventional soil parameters. The effect of retrained dilatancy, which is considered to be the reason for high pullout resistance in dense materials, is negligible in loose fill materials except under very low stress level. Furthermore, pullout resistance increases with overburden pressure opposed to some field test results reported in the literature which show no systematic trend in pullout resistance with overburden pressure. A numerical model was developed to simulate the mobilization of pullout force in soil nails. It has been shown that a simple one-dimensional spring model can be used to simulate the pullout load–displacement relationship.