Performance of Plied-Raft Systems

Piles are one of the widely spread used systems to transfer high levels of stress to deeper soil strata when the subsurface strata cannot bear the needed stress level. Piles are commonly connected using a raft to maintain group action and to ensure overcoming any expected differential settlement. Although the raft is in direct contact with the sub-surface strata conventional design systems ignore the load transferred from the raft to the soil due to this contact and encounter on the pile group bearing capacity and settlement. This system is named as pile group system. The behavior of piled raft system depends on many factors starting from the behavior of a single pile (pile–soil interaction) to the raft-soil interaction and the pile-soil-pile interaction. This fact highlights the importance of studying a single pile load transfer mechanism prior to the study of group action to be able to validate the main parameters used in modeling. To validate the software package used and the estimation of the different input parameters needed for the modeling of different pile group system a pile load test that was performed on ALZEY Bridge in Germany conducted by Sommer & Hammab.