Comparative Analysis of Various Interaction Effects for Piled Rafts in Sands Using Centrifuge Tests

Abstract

In the current study, the load responses and interaction effects of piled rafts embedded in sands were investigated. A series of centrifuge load tests were conducted using different types of model foundations. Single piles, group piles, piled rafts, and unpiled rafts were adopted in the tests to analyze various interaction effects of piled rafts. The load-settlement curves of piled rafts were similar to those of group piles for the initial settlement range and became similar to those of rafts as settlement increased. The pile-group, pile-to-raft, and raft-to-pile interaction factors showed state-dependent and nonlinear variations with settlement. Both pile-to-raft and raft-to-pile interaction factors decreased within the initial settlement range and increased with increasing settlement. The range of pile-to-raft interaction factor values was much larger than the range of values for the raft-to-pile interaction factor. The load response and load transfer relationship of piles for piled rafts were different from those of single piles, showing that the effect of raft-to-pile interaction was more dominant within the upper soil zone. The mobilized factor of safety for rafts was always higher than the safety factor of piles and piled rafts because of the lower mobilized load-carrying capacity of rafts.