Evaluation of Shaft Frictional Resistance Value of Soil Nailing Method on Embankment Ground

Abstract

In order to evaluate the applicability of soil nailing method on embankment ground, pulling tests, digging observation of the fixing body, and comparative evaluation with the geotechnical strength were performed. As a result, the diameter of the fixing body tended to be expand 1.1 times for the cohesive soil, 1.2 times for the sandy soil ground, and 1.3 to 1.4 times for gravel and cobble stone mixture soil compared to the diameter of the drilled hole. In addition, it can be said that appropriate spacer specification for each embankment type, or securing the soundness of the fixing body by outbreak of the tip is necessary. Furthermore, it was found that the surface roughness of the fixing body affects the pulling capacity, and especially the expanded tip shape had a high reinforcement effect. On the other hand, as for the shaft frictional strength (τ value) of the ground which affects the pulling capacity, the evaluation formulas of the N and Nd values were proposed, and it was confirmed that this could be applied to the actual installation work. Furthermore, it was found that the estimated value of the peripheral surface frictional resistance indicated in the cut soil guideline can be applied to the embankment.