Experimental observation and constitutive modelling of the shear strength of a natural unsaturated soil

Ching Yu Chao*, Stefano Muraro, Wout Broere, Cristina Jommi

*Corresponding author for this work

Research output: Contribution to journalConference articleScientificpeer-review

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Increasing frequency and intensity of extreme weather events in the Netherlands is raising attention on the unsaturated response of geo-infrastructures, promoting research projects to provide an overview of the impact of unsaturated conditions on the response of shallow soil layers and embankments, and to better address maintenance and mitigation measures. As part of this effort, we discuss the results of standard laboratory tests performed on initially unsaturated samples retrieved from the field and tested in natural conditions, as well as after controlled drying and wetting. The variation of the "undrained"(i.e. at constant water content) shear strength with the degree of saturation obtained from the laboratory tests aligns well with CPT measurements performed in the field. An elastic-plastic constitutive model with mixed isotropic-rotational hardening developed for saturated soft soils was extended to unsaturated conditions by following a robust approach previously developed for compacted clayey soils. Coupling between the mechanical and the hydraulic behaviour is provided by the water retention curve. The model nicely captures the response observed in the laboratory, until extreme dry conditions, which possibly alter the structure of the soil, the peak stress, and the brittleness after failure. The model is capable of reproducing the effects of the previous hydraulic history on the stress-strain behaviour observed from the laboratory tests over a wide range of degree of saturation.

Original languageEnglish
Article number02001
Number of pages6
JournalE3S Web of Conferences
Publication statusPublished - 2023
Event8th International Conference on Unsaturated Soils, UNSAT 2023 - Milos, Greece
Duration: 2 May 20235 May 2023


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