PhD position – 2025-2028
Long-term inhibition of clay shrink-swell:
Chemo-Hydro-Mechanical modelling and field scale numerical simulations
Context:
The cycles of clay shrink-swell (CSS) are linked to the cycles of soil moisture fluctuations, governed by alternating precipitation and drought periods. In France, 54% of constructions are located in areas characterised by a medium to high hazard of CSS. Structural damages to constructions caused by CSS are estimated at several hundred million euros annually, making CSS the second largest category for natural disaster compensation. In the context of climate change, the increasing occurrences of extreme meteorological events (in intensity and frequency) will exacerbate the vulnerability of constructions to CSS. Managing the risk associated with the CSS geohazard thus constitutes a considerable economic challenge.
Figure 1. Clay shrink-swell mechanisms. © BRGM – M. Villey. (https://www.georisques.gouv.fr/consulter-les- dossiers-thematiques/retrait-gonflement-des-argiles)
This PhD subject is part of the research project IRGAK, funded by the French State as part of France 2030 operated by ADEME (French Agency for Ecological Transition), coordinated by ESTP (https://www.estp.fr/en) and ENPC (https://ecoledesponts.fr/en). The IRGAK project aims to develop an in-situ soil treatment solution to inhibit the volume change of clayey soils during seasonal wetting-drying cycles. Various actions are planned: laboratory tests, field- scale experiments, and predictive numerical simulations to design a treatment protocol considering local geological, geotechnical, and meteorological conditions.
Objectives:
In this context, the present PhD position focuses on performing a comprehensive numerical analysis to model the ability of the treatment solution to inhibit CSS. In particular, the PhD student will:
- Develop and implement a constitutive model for the chemo-hydro-mechanical behaviour of natural expansive clays in a FEM code;
- Calibrate and validate the model through simulations of laboratory experiments performed in the framework of the IRGAK project;
- Implement an advanced soil-atmosphere interactions model and validate couplings between soil behaviour, diffusion kinetics and hydrometeorological conditions through simulations of full-scale experiments performed in the framework of the IRGAK project;
- Use the validated model to perform predictive simulations of the influence of the treatment solution on the long-term inhibition of CSS;
- Propose relevant correlations between model parameters and geotechnical properties measured using standardised laboratory or field tests.
Candidate profile:
The candidate should have graduated in geotechnics, geomechanics, civil engineering, or mechanics, have demonstrated capabilities in numerical modelling, and be interested in both scientific development and its engineering applications.
Supervision:
The PhD will be hosted at ESTP (Cachan, France) from october 2025 to october 2028, and co-supervised by Dr. Benjamin Dardé (ESTP), Prof. Jean-Michel Pereira (ENPC), Dr. Abdelkrim Bennabi (ESTP).
Applications :
Motivated candidates are invited to send a CV, transcript of MSc results and a cover letter to:
