The main objective of this research is to study the mechanical behaviour of tropical soils using elasto-plastic constitutive equations in the so-called limit and critical states. Indeed, researchers of the Cambridge University had noticed that during their various experiments, the rate of volumetric deformation ( ) of the sample tending to zero every time the rupture of the specimen is reached during a test performed on a clay specimen Roscoe et al., 1958. To better understand and clarify this mechanical behaviour, a description has been proposed in the (e, p, q) representation that means void ratio, volumetric stress (spherical pressure) and deviatoric stress. This frame of theoretical study and apprehension is called: the theory of the Critical State. One of the major problems met at the time of our present research is the non-availability of triaxial apparatus allowing us to achieve some tests on tropical soils (samples from Senegal in West Africa) and to describe the behaviour of these materials easily like the researchers of the university of Cambridge in the theory of the critical state. To by-pass this difficulty, we decided to consider two very classical and simple mechanical tests: shear-box and the oedometer test as well as the interrelationship of the results given by the tests and some theoretical calculations. This is a way to identify an elasto-plastic model (the modified Cam Clay model) without any triaxial experiment. Indeed it supposes the model to be suitable to describe the mechanical behaviour of the considered clays.
References
[1]
Roscoe, K.H., Schofield A.N. and Wroth C.P. (1958) On the Yielding of Soils. Géotechnique, 8, 22-53. http://doi.org/10.1680/geot.1958.8.1.22
[2]
Schofield, A. and Wroth, P. (1968) Critical State Soil Mechanics. Lecturers in Engineering at Cambridge University. http://www.civ.eng.cam.ac.uk/geotech_new/publications/schofield8wroth81968.pdf
[3]
Atkinson, J.H., Bransby P.L. (1978) The Mechanics of Soil: An Introduction to Critical State Soil Mechanics. McGraw-Hill Book Company (UK) Limited, Maidenhead, Berkshire, England, ISBN 07 084135 7.
[4]
Fall, M., Tisot, J.P. and Cisse, I.K. (1995) Stress-Strain Behaviour of Three Compacted Lateritic Gravels from Western Senegal Using the Box Machine. Bulletin of International Association of Engineering Geology, 52, 59-73.
[5]
Sikali, F. (1985) Détermination d’un modèle rhéologique pour une latérite compactée par des essais simples de laboratoire. Journées Univ. G. C. “Méc. Sols Appl.” INSA Lyon (22-30 Oct. 1985).
[6]
Fall, M., Tisot, J.P. and Cisse, I.K. (1995) Comportement mécanique à l’appareil de cisaillement de Casagrande de trois graveleux latéritiques provenant du Sénégal occidental. BULLETIN de l’Association Internationale de GéOLOGIE DE L’INGéNIEUR Paris, Octobre 1995, Vol. 52, 59-73.
[7]
Berthaud, Y., De Buhan, P. and Schmitt, N. (2013) Aide-mémoire de mécanique des sols-Dunod Ed. 2e édition, Dunod Ed./L’Usine Nouvelle, collection Aide-mémoire de l’ingénieur, 320 p.
[8]
Baldovin, G. (1969) The Shear Strength of Lateritic Soils. Proc. Of the Spec. Session of Eng. Prop. Of lateritic Soils, Seventh Int. Conf. on Soil Mech. and Found. Eng., 1, 129-142.
[9]
Fall, M., Tisot, J.P. and Cisse, I.K. (1994) Proposition pour une classification des graveleux latéritiques (application au cas du Sénégal). Bulletin of International Association of Engineering Geology, 50, 17. https://doi.org/10.1007/BF02594953
[10]
Ndiaye, C., Fall, M., Ndiaye, M., Sangare, D. and Tall, A. (2014) A Review and Update of Analytical and Numerical Solutions of the Terzaghi One-Dimensional Consolidation Equation. Open Journal of Civil Engineering, 4, 274-284.
[11]
Fall, M. (1993) Identification et caractérisation mécanique de graveleux latéritiques du Sénégal: Application au domaine routier. Thèse de Doctorat de l’I.N.P.L (Institut National Poly-technique de Lorraine/France) en Géni Civil, 240 p.
![\"\"](\"Edit_2681c340-4679-4216-a5fc-9cb187abdf99.bmp\")
) of the sample tending to zero every time the rupture of the specimen is reached during a test performed on a clay specimen Roscoe et al., 1958. To better understand and clarify this mechanical behaviour, a description has been proposed in the (e, p, q) representation that means void ratio, volumetric stress (spherical pressure) and deviatoric stress. This frame of theoretical study and apprehension is called: the theory of the Critical State. One of the major problems met at the time of our present research is the non-availability of triaxial apparatus allowing us to achieve some tests on tropical soils (samples from Senegal in West Africa) and to describe the behaviour of these materials easily like the researchers of the university of Cambridge in the theory of the critical state. To by-pass this difficulty, we decided to consider two very classical and simple mechanical tests: shear-box and the oedometer test as well as the interrelationship of the results given by the tests and some theoretical calculations. This is a way to identify an elasto-plastic model (the modified Cam Clay model) without any triaxial experiment. Indeed it supposes the model to be suitable to describe the mechanical behaviour of the considered clays.
