Performance assessment of single and group of helical piles embedded in expansive soil

Abstract The present work deals with helical piles that extensively used in foundations for structures subjected to both compressive and tensile forces. The behavior of square helical piles models (5 × 5) mm, embedded in expansive soil overlaying a layer of well compacted sandy soil, (single and group of helical piles) were investigated and compared with ordinary piles. Model tests are performed with helical pile length 150, 200, and 300 mm and helix diameters 15 and 20 mm. Helical piles with one helix and double helix were considered. The pattern of helical piles group models consists of four piles in a square arrangement. Thirty-six models of helical pile groups embedded into the expansive soil were performed. It is found that the pile length, number of helix, and helix diameter have a great effect on the amount and rate of uplift movement of helical piles embedded in expansive soil. The deeper helical piles with higher L/D ratios showed greater pullout capacity comparing to the shallower piles. The maximum upward movement of helical piles group is less than that of single pile