Pile Group Interaction Based on Field Monitoring and Load Tests

Abstract

The effects of pile group interaction on settlements were investigated based on the results of two monitoring cases of piled raft foundations and single pile load tests in soft ground. The first case was a piled raft consisting piles embedded in deep dense sand with large spacing supporting a 12-story building, and the case second was a piled raft consisting of friction piles with large spacing supporting a 7-story building. The load-settlement data of the monitored and test piles of different dimensions were compared using a modification factor derived from an elastic solution for the axial response of a single pile. Based on the investigation, it was found that the modified load-settlement data of the monitored piles were generally consistent with the static load-settlement curve of a single pile. Therefore, no significant effects of pile group interaction on settlement were found. In such cases as pile groups with large spacing, single pile load test data can be more useful in the settlement prediction of piled rafts and pile groups. In addition, it was found that the pile head stiffness of the equivalent static load-settlement curve derived from the rapid load testing in clay soils using the UPM was considerably large compared to the stiffness of the static load test curve, as pointed out by previous studies.