Maalej, Yamen (2007) Mechanical behaviour of a grouted granular medium: Experimental study and micromechanical modelling. PhD thesis, ENPC.
Abstract
The injection is a largely used and relatively old process of ground improvement. Generally, a cement grout formulated in order to impregnate the porous network is used. The result is an improvement of the proper ties of the soil by reduction in permeability and an increase of the mechanical resistance of the soil. We present an experimental study for the characterization of the mechanical behaviour of the virgin and injected granular media. A special focus is put on the non linearity of the elastic behaviour and the variation of the behaviour according to the distance from the injection source. A microstructural characterization was carried out aiming at a better understanding of the mechanisms responsible for the reinforcement brought by injection and in order to formulate the micromechanical model. The characterization of the final porosity of the grouted medium was addressed by means of experimental techniques (porosimetrie, image analysis) and through a phenomenological model based on a filtration law. Concerning micromechanical modelling, we were interested in the behaviour of the virgin and injected granular medium at the small deformations and at the rupture characteristics. We proposed a first approach consisting in replacing the solid phase of the granular medium by a selected continuous fictitious solid. The fictitious medium which is equivalent to the real granular medium is then a porous medium made up of the fictitious solid phase and pores. This fictitious medium has the advantage of being described in a continuous manner, winch enabled us to use the traditional techniques of homogenisation of the random media, to model the effects of the introduction of the cementing phase. In a second approach, the granular medium is modelled as a porous polycrystal. The behaviour of the granular assembly is derived from the intergranular law of contact governing the displacement discontinuities in the interfaces when applying a load. The failure properties were addressed for both the virgin and the injected granular media.
| Item Type: | PhD Thesis (PhD) |
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| Thesis Supervisor: | Dormieux, L |
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| Date: | January 2007 |
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| Board of examiners: | Kondo, D and Sckokzylas, F and Hicher, Py and Benhamida, A and Dupla, Jc and Canou, J and Dormieux, L |
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| Collection (Fonds): | ENPC |
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| Institution: | ENPC |
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| Subjects: | 4. Materials Science, Mechanics and Mechanical Engineering |
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| Uncontrolled Keywords: | Granular media, Grouting, Non linear elasticity, Failure, Micromechanics, Microstructure, Homogenization., Milieux granulaires, Injection, élasticité non linéaire, Rupture, Micromécanique, Microstructure, Homogénéisation |
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