Settlement of piled raft subjected to strong seismic motion

Abstract

This paper presents settlement and load sharing behavior of a piled raft supporting a low-rise building subjected to strong seismic motion. On March 11, 2011, the 2011 off the Pacific coast of Tohoku Earthquake struck the building site. Based on the field monitoring results of the piled raft before and after the earthquake, it was found that the foundation settlement near the raft center was increased by 4.1 mm to 24.8 mm while the ratio of the load carried by the piles to the effective structure load was decreased slightly. A mechanism of the increase in settlement of the piled raft subjected to the strong seismic motion is discussed. Using a hysteretic load-unload-settlement curve derived from a rapid load pile testing and a settlement ratio obtained from the results of the pile testing and the field monitoring, the increment in settlement of the piled raft was estimated to be 3.8 mm which roughly agreed with the measured value.