Abstract: In order to explore the calculation method of the inflatable anchor bearing capacity, according to the model test, the stress characteristics and failure forms of the inflatable anchor during pullout are analyzed as well as the variational characteristic of the load displacement curve of anchor. Based on the theory of cavity expansion, the formula for the inflatable anchor side resistance and end resistance calculation are derived through a simplified mechanical model. The calculation values by the theoretical formula are compared with the experimental results. The results of the study show that: (1) the elastoplastic deformation mechanism of the expansion body end to soil can be well described by the spherical cavity expansion theory, as well as the estimation of end resistance value. Due to the inflated pressure on the soil extrusion expansion effect, the anchor side resistance is greatly increased. (2) The results from the ultimate bearing capacity theory formula are coincident with those from the pullout test, so as to validate the ultimate bearing capacity theory formula. (3) With a case of comparison to screw anchor, inflatable anchor shows the 4.3 times of the bearing capacity over single anchor sheet screw anchor and about 1.9 times over double anchor plate screw anchor, so as to show the obvious advantages of the inflatable anchor bearing capacity.

Key words: inflatable anchor, ultimate bearing capacity, end resistance, side resistance, calculation method