Studying the consolidation settlement for multi-layered foundation concerning the change in compressibility within the settlement zones

Abstract

This paper deals with the approach of predicting the consolidation settlement for a multi-layered foundation concerning the change in the compressibility of the settlement layers. This non-linear problem is preliminarily solved by using the Massachusetts Institute of Technology’s (MIT’s) suggestion of approximation, according to which every two layers are converted into a single layer having an equivalent coefficient of consolidation Cv. This paper aims to further the solution by considering the variation of the permeability in the settlement zones of each compressible layer as a change in the compressibility and coefficient of compression. During consolidation, the new value of k is updated, resulting in a new coefficient of consolidation Cv and mv simultaneously; then compressible layers are combined and converted into either equivalent properties or thickness of consolidation. In case the coefficient of volume compression mv is kept to be constant, and the change in the compressibility of the settling zone is taken into account as in this study, preliminary results on the settlement of the alternatives indicate that the consolidation settlement will be greater than that of the conventional approach of analysis and the numerical computation by Plaxis model. The results of the comparison between this study and those of the other models _that are assumed to yield the same time-dependent consolidation_ and numerical model Plaxis indicate that the consolidation for multi-layered foundation requires a more rigorous study. This is a more detailed modification for coming closer to a conservative prediction of the time of consolidation and final consolidation settlement.

Keywords

• settlement zones, permeability, compressibility, equivalent coefficient of consolidation, equivalent thickness of soil layer