Effect of Pile Spacing on the Static Lateral Behavior of Vertical and Battered Pile Groups

The lateral resistance of pile groups is greatly affected by the pile spacing. The presence of neighboring piles at close spacings results in a reduction in the lateral capacity of each pile in the group due to the greater interaction between the piles. In this study, the effect of pile spacing on the static lateral behavior of two pile group configurations (vertical and battered piles) is investigated using finite element (FE) modeling. A total of six three-dimensional FE models were developed in Abaqus version 6.12 for 4 × 4 vertical and battered pile groups at three pile spacings (3D, 5D, 7D), where D is the pile width. The nonlinear pile group behavior was accounted for using elastoplastic constitutive models and pile-soil interface model. The influence of spacing on pile group efficiency, internal axial load in the piles, and p-multipliers is discussed. The results showed that the battered pile group had larger group efficiency (70–90%) than the vertical pile group (40–80%) at all pile spacings. The vertical pile group had a significant boost in pile group efficiency (28%) when the spacing increased from 3D to 5D, while it was 14% in the battered pile group. The internal axial load decreased only in two pile rows in both pile groups with increased pile spacing. The p-multipliers increased with increased pile spacing in both pile groups, in which the rate was highest in the middle and trailing rows.