A simple method to determine soil–water retention curves of compacted active clays

Dias, Ana Sofia; Hughes, Paul N.; Toll, David G.; Glendinning, Stephanie

Abstract

Determining the Soil Water Retention Curve (SWRC) of an active clay constitutes a challenge due to the significant, and sometimes irreversible, volume changes that occur during wetting and drying cycles. A novel yet simple method of experimentally determining the evolution of the SWRCs with moisture cycles is presented based on the results of a rigorous experimental study. Its purpose is to support the modelling of water flux in earthworks exposed to weather cycles that cause deterioration. Firstly, three SWRC branches (the primary drying, a scanning drying, and a scanning wetting branch) are measured and used to fit the proposed generic SWRC semi-empirical model in terms of water ratio, that, in the adsorptive region, is independent of the compaction conditions (void ratio and water content at compaction). Soil Shrink-Swell Curves (SSSCs) in terms of water ratio versus void ratio, that are easy to measure, can be determined for different compaction conditions over several drying and wetting cycles. Finally, the SSSCs are combined with the generic SWRC model to determine the evolution of the SWRCs with moisture cycles for the compaction conditions of interest. This method is demonstrated for two London clays of high and very high plasticity. Samples were compacted in five different conditions, varying in gravimetric water content and dry density, and were cycled six times between 1 and 80 MPa of total suction. The generic SWRC model was fitted to the experimental data. The model was able to estimate the SWRC in terms of degree of saturation over the six drying-wetting cycles without propagation of error. The significance of the research is that SWRC can now be determined over a range of wetting and drying cycles quickly and simply and enable modelling of deterioration of clays fills due to the action of weather to be accurate.

Citation

Dias, A. S., Hughes, P. N., Toll, D. G., & Glendinning, S. (2023). A simple method to determine soil–water retention curves of compacted active clays. Transportation Geotechnics, 43, 101138. https://doi.org/10.1016/j.trgeo.2023.101138

• Journal Article Type: Article
• Acceptance Date: Oct 16, 2023
• Online Publication Date: Oct 18, 2023
• Publication Date: 2023-11
• Deposit Date: Nov 2, 2023
• Publicly Available Date: Nov 2, 2023
• Journal: Transportation Geotechnics
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 43
• Pages: 101138
• DOI: https://doi.org/10.1016/j.trgeo.2023.101138
• Keywords: Geotechnical Engineering and Engineering Geology; Transportation; Civil and Structural Engineering
• Public URL: https://durham-repository.worktribe.com/output/1875185