ANALYSIS FOR SOIL REINFORCEMENT WITH BENDING STIFFNESS

Soil nailing as a method of slope stabilization and repair finds widespread application despite the absence of a clear and unified design approach. The ability of soil nails to increase the shear strength of soil by acting under combined loading, namely, shear and tension, is one of the more controversial aspects of design. For any structural member there is a relationship between the maximum bending moment and axial force, where the bending moment is in turn a function of the shear force in the member. The magnitude of this shear force can be deduced by either an elastic or a plastic model of the soil-nail interaction. The analysis presented in the paper is for both grouted and ungrouted nails, and design equations are given. The finding is that for typical soil-nail diameters only a small proportion of the maximum shear strength of the nail can be mobilized. Expressed in terms of the improvement in soil shear resistance, the benefit from using shear force is found always to be modest when compared with that due to the axial force in the bar.