Calculation method of pull-out bearing capacity of soil nail

Pull-out bearing capacity of soil nail is a key parameter of soil nailing design,the calculation method supplied by the standard is too romantic.Pullout bearing capacity of soil nailing is primarily controlled by interface strength of soil and nail,soil strength around the soil nail,soil press from upper soil and material strength of soil nail.Based on the different conditions,the styles of soil nail pull-out failure can be classified as column shear failure on the interface between soil nailing and soil,soil shear failure around soil nail,composite shear failure and material yield failure of soil nail.Based on Mohr-Coulomb criterion and the hypothesis that the lateral soil press along soil nail is linear,the calculation formula of pull-out bearing capacity of soil nail are developed when soil shear failure around soil nail and composite shear failure happen.Two engineering cases illustrate that the soil shear failure around soil nail happen in most cohesive soil.