Experimental Study on the Behavior of Single Piles Under Combined Torsional and Vertical Loads in Contaminated Sand

Contaminated soil can reduce the stability of structures and infrastructure, endangering their structural integrity. Hence, this study tries to determine how oil pollution influences the torsion behavior of model steel piles at varied soil densities. This study is critical for determining piles' structural integrity and stability in oil-contaminated situations. A mixture of heavy motor oil and clean sand samples was prepared in proportions ranging from 0 to 8% of the dry weight of the soil. In this study, the relative densities (Dr), pile slenderness ratio (Lp/Dp), oil concentration (O.C%), and contaminated sand layer thickness (LC) all varied. The study also includes an examination of piles of combined load (vertical and torsional). Results revealed that the pre-applied torsion force reduced the pile's vertical bearing capabilities. Furthermore, at Dr = 30%, we determined that the maximum vertical load under amalgamated load at constant torsional load T = (1/3Tu, 2/3Tu, and Tu) in cases of (Lc/Lp) = 1 and (Lp/Dp) = 13.3 is 1.67, 3.4, and 5% less than piles under pure vertical load, respectively. This highlights the importance of considering torsional forces in pile design to guarantee precise load-bearing capabilities. Engineers should carefully assess both vertical and torsional loads to optimize the performance and stability of piles in various conditions.