Solution Charts for Finite Strain Consolidation of Normally Consolidated Clays

Abstract

This paper presents graphical solution charts for 1D consolidation of a single homogeneous layer of normally consolidated clay under a surcharge load. Cast in dimensionless form, the charts include the effects of vertical strain, self-weight, and decreasing compressibility and hydraulic conductivity during the consolidation process. To estimate total settlement, the user must specify the initial layer thickness, compression index, initial void ratio at the midheight of the layer, and initial and final effective stress conditions at the top of the layer. To estimate the rate of settlement and distribution of excess pore pressure, boundary drainage conditions and the initial hydraulic conductivity at the midheight of the layer are also required. As a design tool, the charts can be used to make preliminary estimates of settlement and excess pore pressure with fewer restrictive assumptions than for conventional theory. The charts can also be used to verify solutions obtained from numerical analyses. Furthermore, the charts are educational in that they illustrate the effect of different variables on the consolidation process. Using the solution charts, estimated values for settlement are in good agreement with field measurements for a well-documented case study. Estimated and measured values for excess pore pressure are in reasonable agreement during the middle stages of consolidation but are in lesser agreement during the early and later stages.