Effect of Pile Thread Spacing on the Friction Resistance of Minipile

Abstract

This study aims to determine the most effective type of pile foundation between threaded sleeve piles with a 10 cm spacing and threaded pile piles with a 20 cm spacing, focusing on their frictional bearing capacity. Test specimens were prepared using reinforced concrete with a compressive strength of K-350 kg/cm2, reinforced with 4D10 mm longitudinal bars and Ø8-150 mm stirrups. Measurements of pile settlements were taken over several days to assess their behavior under load. Results indicated that piles with a 10 cm thread spacing exhibited a settlement of 3.7 mm on the first day, while those with a 20 cm spacing settled by 4.2 mm, with a percentage difference of 29.6%. The study concludes that rougher surfaces (tighter threads) yield greater frictional forces, thereby enhancing pile bearing capacity. Additionally, settlements tended to stabilize over time, with piles at 20 cm spacing experiencing a quicker cessation of settlement compared to those at 10 cm spacing. This research provides valuable insights for foundation engineering, material technology, and concrete construction practices. It also offers practical implications for the pile manufacturing industry.