Behaviour of under-reamed and helical piles under compressive and tensile loads: A comparative study

This paper presents a comparative study on under-reamed and helical piles under compressive and tensile loads. The study includes single-bulb, single-helix, double-bulb, double-helix, triple-bulb, triple-helix, and conventional pile types. The diameter and length for all the piles were 16 mm and 400 mm, respectively. Experimental studies were performed on the pile models under compressive loads using a tank of size 0.5 m × 0.5 m × 0.5 m. A numerical analysis was also conducted under compressive and tensile loading. The presence of bulbs and helices influenced the compressive and tensile behaviour of the piles. Under compressive loading conditions, it was observed that the triple bulb had a load-carrying capacity 5.5 times higher than the conventional pile and 4.7 times higher than the triple helix for the same settlement values. Comparing the load-carrying capacity of triple-bulb and triple helix piles under tensile loading, it was found that the former increased by 674% and 577%, respectively, over conventional piles. It has been observed that as the number of bulbs or helices increases, the pile’s settlement is reduced.