Numerical study on bearing performance of rock socketed pile anchored by inclined anchors under uplift and horizontal combined load

Rock-socketed pile anchored by inclined anchors (RPIA) is a novel pile-anchor composite foundation developed to address the challenges of transmission tower installations in mountainous areas. This study investigates the bearing performance of RPIA under uplift-horizontal combined load using a nonlinear numerical model validated through full-scale field tests. Parametric analyses were conducted to examine the effects of inclined anchor length, angle and diameter, as well as connection node depth, on RPIA performance. Analysis reveals that inclined anchors reconstruct the path of potential slip surfaces within soil and rock mass, thereby effectively expanding the participation range of geotechnical bodies. Parametric analysis demonstrates that ultimate load of RPIA decreases with increasing angle, but increases with larger length and diameter of inclined anchor. The trends are further modulated by the relative position of the connection node within the geotechnical body. Longer inclined anchors shift the failure mode of the RPIA from the pull-out of short pile to the yielding of longitudinal rebar, and are suitable for shallower connection nodes to improve horizontal resistance. While shorter inclined anchors require the increment in anchor diameter and depth of connection point. The results of this study provide guidance for the design and promotion of RPIA.