Modeling and Implementation of the Isotache Concept for Long-Term Consolidation Behavior: Fid-Bau Portal

Modeling and Implementation of the Isotache Concept for Long-Term Consolidation Behavior

Watabe, Yoichi / Leroueil, Serge

Abstract

A practical use of the isotache concept in creep settlement prediction is newly introduced in this study. The isotache concept introduces a unique relationship between the strain and the consolidation pressure corresponding to the strain rate in association with viscosity. The authors have proposed a method to simply introduce the isotache concept, which uses a compression curve normalized by preconsolidation pressure $[ε - \log (σ^{'} / σ_{p}^{'})]$ and a strain rate dependency relationship between the preconsolidation pressure ( $σ_{p}^{'}$ ) and strain rate ( $\dot{ε} = d ε / dt$ ). The strain rate dependency relationship is modeled as an equation based on power law. According to the authors’ method, the slope of the strain rate dependency relationship ( $\log σ_{p}^{'} - \log \dot{ε}$ ), which coincides with $C_{α e} / C_{c}$ , can be calculated as a function of strain rate, showing that $C_{α e} / C_{c}$ is not constant but decreases with decreasing strain rate. In engineering practice, consolidation settlement is generally estimated based on the compression curve obtained from the 24-h incremental loading oedometer test, which corresponds to a strain rate of about $1 \times 10^{- 7} s^{- 1}$ . Using the compression index $C_{c}$ at the consolidation pressure and initial void ratio $e_{0}$ , creep settlement can be easily calculated as a function of $C_{c} / (1 + e_{0})$ and in situ strain rate (several orders of magnitude smaller than $1 \times 10^{- 7} s^{- 1}$ ).