Lateral Pullout Tests and Modeling Failure Modes for Nongrouted Anchor Nails in Flexible Protection System

This paper presents an investigation into the influence of the size of nongrouted anchor nails on the role of anchorage capacity in a flexible protected system. A lateral pullout test was used to examine the deformation, pullout capacity, and failure mode of anchor nails with different lengths and diameters. There could be three failure modes, namely rotation failure, bending failure, and tension failure. The theoretical models were established for different failure modes, and a corresponding solution for critical pullout force was derived. Moreover, the applicability of the theoretical models was verified by the consistency between the measured value and calculated value, which seems to show that the models could predict the displacement and the resistance of anchor nails under lateral force. With a fixed diameter, an increase in the length of the anchor nail contributes to a longer bending length, but the ratio of bending length to total length is consistent with the variation of the ultimate pullout capacity—both of which increase first and then decrease. On the contrary, length unchanged, the bending length and the ratio of bending length to total length decrease with a larger diameter, while the ultimate pullout capacity increases.