ANALYSIS OF DOWNDRAG ON PILE GROUPS BY THE FINITE-ELEMENT METHOD

The downdrag on friction and endbearing pile groups was investigated, based on a numerical analysis. The emphasis was on quantifying the red uction of downdrag on pile groups, with a flexible pile cap, due to gr oup effect. The case of a single pile and, subsequently, the response of groups were analyzed by developing interaction factors obtained fro m a three-dimensional nonlinear finite element study. Based on a limit ed parametric study, it is shown that the downdrag on piles in a group is much less than the downdrag on a single pile and is highly influen ced by the group spacing, fetal number of piles, and the relative posi tion of the piles in a group. In light Of all these influencing parame ters, a simple method is recommended for square groups of 9-25 piles w ith spacing-to-diameter ratios of 2.5 and 5.O for downdrag loads. (C) 1997 Elsevier Science Ltd.