Lime treated soil as an erosion-resistant material for hydraulic earthen structuresReport as inadecuate

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1 Recherche et Développement 2 IFSTTAR-GER - Département Géotechnique, Eau et Risques 3 LR Blois - Laboratoire Régional des Ponts et Chaussées de Blois 4 LAEGO - Laboratoire Environnement Géomécanique et Ouvrages 5 UR OHAX - Ouvrages hydrauliques et hydrologie 6 CIH-EDF - Centre d-Ingénierie Hydraulique Savoie Technolac

Abstract : This paper deals with the recent research results obtained through SOTREDI research project -SOil TREatment for DIkes- undertaken by the Lhoist Group, a lime producer, in collaboration with several research centres and universities. Lime-treatment of soils is a process that improves the workability of clayey materials and imparts them strong mechanical properties after compaction. These benefits are well known and are used extensively worldwide for the construction of embankments for roads, highways, railways, industrial platforms… However, little is known about the way lime-treated soils behave in the context of hydraulic structures, where the properties of the materials vs water have to be determined. In a first part of the project, it was demonstrated that lime-treated soils could reach permeability levels equivalent to those of untreated materials i.e. 10-9 m-s to 10-10 m-s as measured in the laboratory provided the right moisture content and compaction procedure were used. Full-scale trials showed the feasibility of the procedure at the industrial level. Thanks to the use of modern technology - new mixing plant stationary or mobile and kneading compaction - offering a guarantee of homogeneity, adequate textural properties and conditions for placing the materials were obtained. Following this procedure, a real-scale dike was built in September 2011, to validate the applicability of lab results at full scale. In-situ and laboratory on cored samples mechanical and hydraulic measurements are in progress on this structure. This experimental embankment is the subject of a first companion paper by M. Froumentin et al. with the Centre d’Expérimentation et de Recherche CER. In a second part of the project, the effect of the lime-treatment against various failure mechanisms, in particular internal or external erosion, could be highlighted by a series of results: - the shrinkage limit of soils was shifted towards higher moisture contents, well above the optimum moisture content - the material becomes non-dispersive in the standard Crumb-test, even only 1 day after treatment - the critical shear stress for erosion is increased by one to two orders of magnitude in the Hole Erosion Test and Jet Erosion Test, strongly reducing the risk of piping. Details about these results are described in two other companion papers by S. Bonelli et al. Irstea and C. Chevalier et al. Ifsttar. In parallel, the durability of lime-treatment can be observed after more than 30 years on the Friant-Kern irrigation canal in California, as described in a fourth companion paper by G. Herrier et al. Finally, the data described in this paper strongly suggest that lime-treated soils could be successfully used in the design of earthen hydraulic structures namely canals, dams, dikes and levees.


Author: G. Herrier - C. Chevalier - M. Froumentin - O. Cuisinier - S. Bonelli - J.J. Fry -



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