Abstract

Micropiled-Raft (MPR) foundations are economical and easy to install. In this study, the load sharing mechanism of micropiled-raft foundations in sand was examined. A series of experimental tests were performed on small-scale models in sand with different relative densities. The effects
of micropile spacing and relative density of the sand on the overall load-settlement behavior and the load-sharing mechanism were examined.

The experimental test results served to validate a series of numerical models, which were employed to produce data for a wide range of governing parameters. The effects of the micropile spacing ratio, the relative density of the sand, and the thickness of the raft were examined. While the raft stiffness only marginally affects the overall load-settlement behavior, yet, the load sharing is impacted.

Finally, the Poulos-Davis-Randolph (PDR) method was evaluated against the data produced by the numerical models. It was concluded that the PDR method was occasionally capable of determining the axial stiffness of the MPR with an acceptable range of error, however in general, it overestimated the axial stiffness of the MPRs. Thus, a modification factor was proposed which was validated by the present experimental results