ANALYSIS OF DOWNDRAG ON PILE GROUPS

This Paper describes a new iterative procedure for the analysis of the downdrag forces in end-bearing pile groups, Special emphasis is place d on the rate of increase of downdrag forces with free field soil sett lement, Pile-soil-pile interaction is modelled using Mindlin's elastic solution for a point load in an elastic half-space, Pile-soil slip is taken into account by limiting the shaft friction at the interface, P arametric studies were conducted to elucidate the parameters that gove rn the relationship between free field soil settlement and downdrag fo rces induced in a pile group, Results indicated that interior piles of a large pile group experience relatively small downdrag forces, espec ially when the pile spacing is small, The validity of the proposed met hod is demonstrated by back-analysing two model studies of negative sk in friction on pile groups, The proposed method is also validated agai nst the field test results of a 38 pile group, The computed results sh ow an encouraging degree of agreement with the experimental data.