Numerical Investigation of Drilled Shafts Near an Embankment Slope Under Combined Torque-Ateral Load Scenario

Mast-arm assemblies used for the support of highway signs, signals, and luminaires are exposed to both torsion and lateral load due to wind loadings. Hence, foundations for overhead cantilever structures should be designed for coupled torsion and lateral load scenario. In some cases, mast arm cantilevered structures are installed near or on an embankment slope which might have more concerns on the torsional and lateral resistance of the foundation. Nevertheless, hardly any research works have addressed the issue of drilled shaft foundations under torsion-lateral load case with an embankment in proximity. Therefore, numerical investigation of three cases with different soil layers was performed to: (1) understand the combined torque-lateral load behaviour of drilled shafts near an embankment slope; (2) examine the effect of both the torsion and lateral resistances in the proximity of an embankment slope. The effect of slope on torsional/lateral resistance was studied by numerical analyses. The results showed that increase of the embankment slope lead to the reduction in both torsional and lateral resistance. Finally, design criteria (e.g., minimum allowable distance from the embankment, maximum allowable point load near the embankment) of the mast arm assembly and loads are provided. All three cases demonstrated the decrease of tolerable point load with increase of the slope angle