Application of Back-Analysis to Several Test Embankments on Soft Clay Deposits

Abstract

This paper investigates the practical use of the back-analysis through the trial applications of the analysis to six test embankment projects on soft clay deposits. The method of back-analysis previously proposed by the authors, estimates the Young’s modulus, the Poisson’s ratio and the permeability in multiple soil layers from the monitored movements of subsoil under consolidation. At first, the back-analyzed soil parameters are compared with the ones obtained from the results of laboratory tests. For instance, the 10 times value of permeability estimated from the oedometer tests gives a good approximation to the back-analyzed permeability. However, there is no clear relationship between the back-analyzed Young’s modulus and the one estimated from the laboratory test results. Secondly, the changes in soil parameters during the consolidation are studied by use of the soil parameters back-analyzed at the several stages of construction. For example, the decrease in deformation moduli with the progress of consolidation can be well represented by employing the hyperbolic stress-strain relationship. Thirdly, the possibility of applying the back-analysis to the observational procedure in construction phase is shown using the trend of changes in soil parameters during the consolidation.