Piled rafts in overconsolidated clay: comparison of <i>in situ</i> measurements and numerical analyses

Abstract

This paper presents the results of detailed back-analysis, using three-dimensional finite-element analysis, of three piled raft foundations on overconsolidated clay. Comparisons of overall settlement, differential settlements and the load carried by the piles show reasonably good agreement, although the finite-element analyses generally show a higher proportion of the overall load being carried by the piles than estimated from the field measurements. Three main performance indicators of the piled raft are proposed: the proportion of load carried by the piles, and the maximum settlement and maximum differential settlement, both as a proportion of the corresponding quantity for an unpiled raft foundation. The last indicator, in particular, suggests that improved layout of the pile support can lead to a reduction both in the maximum differential settlement and in the overall quantity of piles. This is illustrated for one of the case histories.