Settlement of Raft Foundations

Abstract

Recent multistory structures built in the City of Adelaide, South Australia, have frequently been founded on rafts. The authors have measured settlements on three such structures, and on two of the three sufficient exploration and test data were available to permit a review of techniques used for settlement prediction. For two of the projects conventional surveying techniques were used; for the third a borehole extensometer technique developed in the United Kingdom was the primary technique. The extensometer approach was found to be superior from a number of standpoints, including accessibility during construction, convenience of measurement and accuracy of results. An alternative method is proposed for settlement prediction and is demonstrated to be simple, versatile and to give results similar to those obtained from currently used methods that are either more restrictive or more time consuming in their application.