Abstract:
Helical piles provide restraint to structures that are subjected to either tension or compressive axial loading. Helical Piles can be a popular choice to use for new construction in High Expansive Clay Soil (HECS). The objective of this paper is to determine the performance of helical piles installed in HECS in terms of vertical movements impacted by surrounding soil volume changes. Due to the expansive soil distribution map, most areas in Central Mississippi, Alabama, and Louisiana are covered by expansive clay, which is well known for its high swelling and shrinking caused by changes in water content due to seasonal variation. To evaluate the performance of Helical Piles in HECS during this study, 30 piles with single and multiple helices with different diameters were installed at different depths to monitor the movement of the piles with seasonal moisture variation. After installation, the performance of the helical pile is monitored with the topographic survey. During the monitoring period, the rainfall and soil moisture variations were also monitored through field instrumentation. Based on field instrumentation monitoring results, the soil was observed to have a constant moisture content throughout the monitoring period, which signifies that the soil has limited volume changes. Based on the field performance monitoring results, it was observed that piles with two or three helices undergo very minimal displacement and piles that are installed below the wetting zone experienced no movement. Therefore, in order to obtain maximum performance of helical piles in HECS, multi-helix piles should be installed within the wetting zone are recommended.