Numerical Study on Effect of Axial Loading on Rock-Socketed Piles in Two-Layered Soil Slope

Piles are commonly subjected to a combination of axial and lateral loading. Therefore, it is essential to understand the effect of combined loading on piles. Previous researches have reported a reduction in the lateral load capacity for the piles situated in the proximity of sloping ground, and rock-socketing has been identified to be a viable solution to overcome the same. Therefore, in this study, through parametric three-dimensional FEM analyses, the response of rock-socketed piles subjected to pure lateral and combined loading has been studied with importance to its effect on the lateral load capacity. The pile is modelled onto a multi-layered soil stratum partially sloping at 1V:1.5H. The position of the pile corresponding to the crest, depth of socketing, and the ratios of axial load acting on the pile have been considered as variable parameters. The position of the pile was varied between 15 pile diameters on the embankment (+ 15D) until three pile diameters on the sloping ground (-3D). The depth of socketing of the pile was introduced at one pile diameter (1D) and improved to two and three pile diameters (2D, 3D) and compared to the response of un-socketed piles (US). The axial loading was applied at 0.4 and 0.8 times the ultimate axial load (0.4Vult, 0.8Vult) and compared to the response of piles under pure lateral loading (PL). The study was performed on short, intermediate, and long pile cases under identical conditions by varying the L/D ratio. The pile was modelled as a linearly elastic body and the soil strata using the hardening soil-small strain material model. Based on the results, it was observed that the effect of axial loading was predominant under short pile conditions and notably significant on the piles situated at positions on the sloping ground. Also, it further reduces the zone of influence due to slope.