Vertical Uplift Capacity of Two Nearby Horizontal Strip Anchors Using the Method of Stress Characteristics

The present study addresses the effect of interference on the uplift capacity of two closely spaced horizontal strip anchors embedded in cohesionless soil. The analysis has been performed using the method of stress characteristics coupled with the limit equilibrium approach. The method consumes fewer assumptions and provides a zone in which the force equilibrium and plastic yield conditions are simultaneously satisfied for given boundary stresses. The effects of surcharge and unit weight of soil on the pullout resistance of anchors have been determined in terms of uplift capacity factors ($F_q$ and $F_{\gamma }$) and are presented as functions of embedment ratio ($\lambda$) and angle of internal friction of soil ($\varphi$). Similarly, the interaction phenomenon of two closely placed anchors has been expressed in terms of efficiency factors (${\xi }_q$ and ${\xi }_{\gamma }$). A detailed parametric study has been carried out by varying the clear spacing ($S$) between two anchors, embedment ratio, and soil friction angle. The results of the numerical analysis are compared with the available theoretical and experimental data reported in the literature.