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logo LGM logo LGM UNSAT unsat-lime Lime treatment of unsaturaded compacted soil
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Bertrand François

Mohamed Oualmakran

Collaboration Prof. J.M. Fleureau (Ecole Centrale, Paris)
Description
In this study, we use the concepts of unsaturated compacted soil mechanics and extend them to consider their lime-treatment. Unsaturated soils are multiphasic and heterogenic materials. These characteristics imply an important complexity of the soil behavior. Indeed, the mechanical response depends on the water retention behaviour. In addition, the microstructure of the soil, affected by the way the soil is compacted, plays also an important role on its mechanical behaviour. The stress-strain relations obtained from experimental tests (triaxial tests, oedometric compressions, uniaxial compressions) are used as input values for the development of the model.

This work is divided in two main parts. The concepts of unsaturated soil mechanics are first applied to untreated soil. So doing, a behavioural law for compacted unsaturated soil is developed. Then, this constitutive framework will be extended to the consideration of the soil treatment with lime.

The soil suction (linked to its water content) is a key parameter that relates the behaviour of both untreated and treated materials (the efficiency of the treatment with lime being strongly related to the water content of the material). So, a rigorous quantification of the water retention curve (relating suction to water content or degree of saturation) is essential.

The constitutive developments are based on a well-validated constitutive law for unsaturated soils: the Advanced Constitutive Model for Environmental Geomechanics- Suction effect (ACMEG-S) (François and Laloui, 2008). From this law, microstructural and lime treatment dependencies are introduced as state parameters in the constitutive relations. Consequently, the objective of this work is to obtain a constitutive stress-strain law that integrates the effects of soil microstructure, water content, lime content and curing time.

 

oualmakran

Microstructure of a lime-treated clayey soil (De Bel, 2007)

 

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Suction effect on the elastic domain

   
Support
  • This project (PhD thesis) is funded by the Fonds National de la Recherche Scientique (F.R.S.-FNRS)
   
Selected publications François B., Laloui L. (2008) ACMEG-TS: A constitutive model for unsaturated soils under non-isothermal conditions. International Journal for Numerical and Analytical Methods in Geomechanics, 32: 1955-1988.

De Bel R., Bollens Q., Gomes Correia A., Duvigneau P.H., Verbrugge J.C (2007) Time and temperature dependency of the geomechanical properties of silty soils treated with lime, Proceedings International Conference on Adavance Characterization of Pavment and Soil Materials, Athènes, Taylor & Francis / Balkema, Vol 1, pp 513-521.