Monitoring of Load Transfer in Piled Raft Foundations

Abstract

Piled raft foundations have proved to be an economical alternative comparing to the conventional foundation schemes. The piled raft system transfers and redistributes the loads from the superstructure to the underlying ground through both the piles and raft. The piles transfer the load to deeper soils mainly through shaft friction while the ground soil beneath the raft supports the load by its bearing capacity. It is believed that by increasing the amount of load taken up by the raft, the number or length of piles could be reduced for cost saving yet without scarifying the safety margins of the system. In this study, a full-scale long term monitoring has been undertaken in Hong Kong to continuously monitor the load transfer during the construction of a low-rise building supported by a piled raft system. Load cells and earth pressure cells were installed on the pile head and between the ground and pile cap respectively to examine the load distribution during the construction. The data provides an opportunity to shed lights on the load transfer mechanisms of a piled raft foundation system.