Numerical study of the influence of soil dilation angle and grouting pressure on the pull-out strength of the soil nail

Soil nailing is an in situ reinforcing technique that is widely used for stabilizing slopes and excavations. The nail-soil interface shear strength, that is, the pull-out strength of a soil nail is an important parameter which controls the design of a soil nailing structure. For drill-and-grout soil nails, the dilatancy of soil and grouting pressure are two important parameters which influence the pull-out strength. Based on the laboratory pull-out tests, a 3-D finite element model was established to investigate the influence of these two parameters on the pull-out strength of a soil nail. Before the parametric study was carried out, the model was firstly validated by comparing measured and simulated results. The agreement between the measured and simulated results was fairly good. The parametric study showed that the peak pull-out stress increased significantly with the increase in grouting pressure and dilation angle of the soil.