Abstract
Laboratory model test results for the ultimate uplift capacity of group piles embedded in clay have been presented. The length-to-diameter ratios of the group piles tested under this program have been kept at 12 and 15. The group uplift efficiency varies with the embedment ratio, number of piles in the group, and the center-to-center spacing of the piles. For the present tests, a group efficiency of about 100% is reached at a center-to-center spacing of 6 to 7 pile diameters.
