Nguyen Pham, Phong Thao (2008) Research in situ and in laboratory of natural clayed soil behaviour at small strain level. PhD thesis, Laboratoire central des Ponts et chaussées, ENPC p.233.
Abstract
The comprehension of soils and structures behaviour as well as soil-structure interactions therefore becomes a growing and important role in the geotechnical research. This requires a reliable and pertinent estimation of soils deformation and resistance characteristics. The determination of mechanical parameters, especially modulus and knowledge of its evolution from small to large strains and variation according to the stress paths followed become important issues. To obtain the parameters characterizing the deformation and rupture of soils, two methods are currently proposed as follows:
- Intact soil sampling and sophisticated laboratory tests,
- In situ testing more or less rustic.
This thesis presents a study of the behaviour of a natural clay of Cubzac-les-Ponts experimental site using different tests allowing the investigation in laboratory and in situ of the small strains range. The idea is to realize tests in laboratory with devices such as consolidometer, triaxial with local measurement system, and and in situ with innovating equipments such as the self-boring pressuremeter (P.A.F 2000), the triaxial in situ (T.I.S) and slotted tube with inside disintegrating tool and mud circulation (S.T.A.F).
Laboratory studies permitted to determine the shape of the yield surface and the soil behaviour when the stress path attains this surface. Attention was paid to analyze the evolution of the yield surfaces with soil loading history, test procedure and to study the variation of the modulus with strain levels, depth of samples, and stress path. For in situ tests, the new self-boring pressuremeter (P.A.F 2000), equipped with radial transducers and geophones allowed establishing a continuous profile of the modulus from small to large strains. The triaxial in situ (T.I.S) tried to recreate in situ the geometry, boundary conditions of a triaxial test as in laboratory and to realize all types stress path imposed during triaxial tests.
Our work presents a data synthesis collected from different tests in laboratory and in situ, and methods to investigate different strains levels also its evolution.
| Item Type: | PhD Thesis (PhD) |
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| Thesis Supervisor: | Magnan, J.-p. |
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| Date: | 10 January 2008 |
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| Board of examiners: | Benoît, J and Levacher, D and Flavigny, E and Reiffsteck, P and Magnan, J.-p. |
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| Collection (Fonds): | ENPC |
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| Institution: | ENPC |
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| Department: | Laboratoire central des Ponts et chaussées |
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| Subjects: | 8. Earth Sciences and Environmental Engineering |
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| Uncontrolled Keywords: | Mécanique des sols, Rhéologie, Essai triaxial, Piézo-éléctriques, Colonne résonnante, Oedomètre, Pressiomètre autoforeur, Triaxial in situ, Surface de charge, Chemin de contraintes, Petites déformations, Modules de déformation, Interactions, Soil mechanic, Rheology, Triaxial test, Bender elements, Resonant column, Selfboring pressuremeter, Triaxial in situ, Yield surface, Stress paths, Small strain, Moduli. |
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