Abstract

Group action of piles driven in sand has been a challenging research subject in the field of geotechnical engineering for the last 50 years. In the literature, planar geometry was the only governing factor to estimate the group capacity, ignoring the contributions of the pile cap rigidity and sequence technique for driving the piles in a group. Accordingly the available theories failed to provide accurate prediction. A numerical model was developed to incorporate the above-mentioned ignored parameters. Furthermore, the distribution of the column load on the individual piles under the pile cap was examined. The results of this analysis showed that in a line pile group, the interior piles will carry more load than those at the exterior boundaries, depending on the rigidity of the pile cap. For a relatively rigid cap, these phenomena existed at a much lesser extent. A design procedure is proposed to determine the pile group efficiency for a given sequential bored piles installed in sand. An optimum cap thickness of a pile group is suggested to achieve the most economical design. Considering the results obtained from the numerical model an analytical model was developed to predict the group efficiency of line pile group. The predicted values by the proposed formula compared well with the numerical test data. Design procedure is given for practical use