Study on the Influence of Thread Length on Vertical Bearing Characteristics of Threaded Piles

ABSTRACT This study investigated the influence of thread length on the bearing capacity and soil deformation mechanism of a single pile based on indoor semi‐pile model tests and numerical simulations combined with digital image correlation (DIC) techniques. The distribution pattern of the soil displacement around the pile and the failure characteristics of the surrounding soil were analyzed, and the axial force transmission characteristics of the pile body were revealed. This study explored the effects of threaded parameters, such as thread length, height, and spacing, on the pile‐bearing characteristics. The results showed that increased pile displacement causes radial cracking and expansion of the surrounding soil, along with an expanded displacement field. Longer thread lengths improved the ultimate bearing capacity and material utilization of the pile; however, the enhancement decreased, and the optimal range was 150–180 mm. As the thread height increased, the increase in the ultimate load capacity decreased, and the optimal thread height for balancing material use and capacity was 8 mm. The bearing capacity peaks at a spacing‐to‐diameter ratio of 1.0. These findings provide a theoretical basis and a direction for engineering optimization for the design of the structural parameters of threaded piles, considering bearing capacity improvement and material economy.