Full-Scale Lateral Load Tests of Pile Groups

Twenty 10BP42 steel piles were driven in cohesive soil, six piles in each of three groups and two isolated single piles (one vertical and one batter). Two of the pile groups consisted of piles spaced 3 ft (0.9-m) apart and one group consisted of piles at 4-ft (1.2-m) spacing. The third group also featured a 3-ft (0.9-m) spacing but four of the piles were battered, 3.5 vertical to 1 horizontal. The results indicate that each pile in a group with 4-ft (1.2-m) spacing had a lateral load resistance approximately 3 to 6 times that of a single isolated vertical pile; for a group having 3-ft (0.9-m) spacing, the lateral capacity per pile was only about twice that of a single pile. For a given lateral load, the pile group with batter piles deflected laterally only 1/3 to 1/2 as much as the pile group with vertical piles only. The maximum positive moments in the piles in the group with 3-ft (0.9-m) spacing (Group II) were 1.6 times those in the piles with 4-ft (1.2-m) spacing.