Oblique tensile tests on model anchor piles in calcareous sand deposits

Offshore anchor piles are extensively used as moor-floating structures in harsh environments that experience oblique tensile loads and the mechanical response is complex. This study investigated the effect of oblique tensile loads on the response of anchor piles in calcareous sand through a series of model tests and the standard penetration tests (SPT) to obtained bearing capacity equations. Eight model piles were installed into the calcareous sand bed with relative densities (Dr) of 53%, 75% and were loaded with different load inclination angles (alpha). The test results showed that the load-displacement curves were nonlinear and that dense sand could effectively control deformation and improve the bearing capacity. The critical load inclination, corresponding to the maximum load capacity for a given pile under tension loading, was around 30 degrees and was larger than that for the terrestrial sand (5 degrees -10 degrees), which may have been caused by particle breakage. The bending stress of the anchor pile was 2-8 times the axial stress. In dense sand (Dr = 75%), the bending moment reaches its maximum around the critical angle (30 degrees), indicating a the strong interaction between the pile and calcareous sand. The ultimate tensile load of anchor piles is a function of load inclination angle and ultimate capacity of uplift and horizontal piles.