Re-examination and analysis of test data on consolidation of soft soils exhibiting creep with different thicknesses

Abstract

Accurate prediction regarding the long-term settlements of soft soils is challenging. One of the reasons for this is time-dependent soil behaviours. How to extrapolate such behaviours from thin laboratory testing with limited timescales to an in situ thick soil layer with large timescales is still an ongoing debate, which can be dated back to the work of Ladd and co-workers in 1977. Many experimental results that were previously used to advocate hypothesis A have been re-analysed and found to align with hypothesis B. However, discrepancies remain in some historical data, particularly in the case of Osaka clay retrieved from the seabed under the Kansai international airport islands. This study begins by introducing the main implications and selected existing models for the time-dependent behaviours of soft soil. It then focuses on the re-examination of selected test results from the work of Watabe and co-workers in 2008, supplemented by numerical simulation using isotache models. The analysis emphasises the importance of considering equal initial conditions when comparing data from samples with varying thicknesses. Furthermore, the good agreement observed between measured data and the simulation results using hypothesis B methods demonstrates the validity of hypothesis B for predicting the long-term consolidation behaviour of soft soil both in the laboratory and at field scales.