Numerical Analysis of Torsionally Loaded Drilled Shafts Near an Embankment Slope in Cohesionless Soils

摘要

Foundations for mast arm/overhead cantilever structures supporting highway signs, signals and luminaires in hurricane prone areas should be sufficient to resist the torsion and lateral load caused by severe wind loading. In some instances such structures are to be installed on top of highway Embankment and the proximity of Embankment slope may adversely influence the torque resistance of the foundation. However, the degree of reduction in torsional resistance due to the closeness of a slope was unknown. A numerical investigation of drilled shaft foundations supporting mast arm structures located near an Embankment slope in cohesionless soils was performed. The torque resistance was found to reduce by a maximum of 22% when the slope angle was varied from 0°-34° (i.e., 0-1V:1.5H). The study revealed that the degree of reduction is a function of the Embankment height and the distance between the shaft face and the crest line whereas, independent of the friction angle of soil. It was also identified that the equivalent level ground approach typically used in the industry practice is adequate for smaller Embankment heights but over-predicts in case of larger Embankments.