Mechanical behavior analysis of vertical fully grouted anchor under pullout load

Considering the changing characteristics of the mechanical properties of rock-soil with depth, it is assumed that the shear stiffness and ultimate shear stress of the rock-soil around the vertical grouting anchor increase exponentially with depth. At the same time, based on the assumption that the shear stiffness in the plastic deformation zone decreases exponentially from the depth of the plastic deformation zone to the top of the anchor, the pull-out mechanical behavior of the vertical grouting anchor is theoretically analyzed. Through engineering case analysis, the rationality and accuracy of the hypothetical model in this paper are verified. And on this basis, the influence of the depth variation coefficient on the shear stress distribution of the anchor was further analyzed. The results of the study show some of the following conclusions. (i) If the mechanical properties of the rock-soil around the anchor increase with depth are not considered, the ultimate pull-out force of the anchor may be underestimated, resulting in unnecessary waste; (ii) the depth variation coefficient has a great influence on the shear stress distribution form of the anchor; (iii) considering the characteristics of the mechanical properties of rock-soil as the depth increases is beneficial to improve the working behavior of the anchor, and can more truly reflect the load transfer process of the anchor. Reasonable consideration should be given in the design and calculation of the vertical grouted anchor.