Experimental and field studies on the behavior of drilled displacement piles

Piles or deep foundations are elements for transferring the load of structures to the substructure and soil layers with more suitable conditions to guarantee the stability of the structure and provide proper service by them. In this regard, the driven and bored piles are commonly used, but high noise and vibration of the driven piles, as well as difficulties and limitations in implementation of the bored piles, have led to the use of a new alternative type of piles installed in the soil using torque and a small amount of compressive axial force. Helical and drilled displacement piles can be mentioned as new types of these piles. Considering the increasing use of these piles, still a few studies have been conducted on them and there is a need for further research on their behavior in different soils and conditions. Therefore, in the present study, in two field and experimental sections, behavior of these piles was evaluated by performing tensile and compressive loading tests. Three models of helical, Tsubasa, and drilled displacement pile were implemented and loaded in experimental section in the frustum-confining vessel of the Amirkabir University of Technology (FCV-AUT) and were compared with the previous works in field section. Our results revealed that drilled displacement pile had better performance than other piles under tension and compression, and it had harder behavior and better capacity than the other two piles in both experimental and field conditions. Also, the required torque of this pile had higher values compared to other piles.