An equivalent model and back-analysis technique for modelling in situ consolidation behavior of drainage-installed soft deposits

Abstract

The predicted consolidation behavior of in situ soft clay, is quite different from that measured, mainly due to the approximate numerical modelling techniques used, as well as the uncertainties involved in soil properties and geological configuration. In order to improve the prediction in two dimensional analysis, this paper fakes these into consideration as follows: (1) an equivalent and efficient model is considered to incorporate three dimensional effects and (2) a back-analysis scheme is adopted for characterizing in situ properties by measurements. An approximate model is developed so that the results of the two dimensional analysis are equivalent to the three dimensional behavior, which is estimated by the ABAQUS program. To simulate the effect of three dimensional characteristics, an equivalent permeability concept and an adjusted width of drainage are applied to the drainage-installed soil deposits. The soil parameters used in the modified Cam-clay model, which have an effect on the process of consolidation, are back-analysed by a BFGS scheme on the basis of settlements and pore pressures measured in real sires. The developed equivalent model and the back-analysis scheme have been implemented in a numerical method of the finite element analysis. It has been found that one may be able to appropriately predict the consolidation behavior of drainage-installed soft deposits. (C) 1997 Elsevier Science Ltd.