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Résumé. Le matériau argileux, dur et cassant lorsqu'il est asséché, présente la particularité de voir sa consistance se modifier en fonction de sa teneur en eau. Un certain degré d'humidité peut le transformer en un matériau plastique et malléable. Ces modifications de consistance peuvent s'accompagner, en fonction de la structure particulière de certains minéraux argileux, de variations de volume plus ou moins conséquentes qui se manifestent soit sous forme d'une forte augmentation de volume (phénomène de gonflement) lorsque la teneur en eau augmente ou de rétrécissement (phénomène de retrait) en période de déficit pluviométrique marqué. Ce comportement est lié essentiellement à certains paramètres environnementaux de ces sols à l'exemple de la géologie et de la lithologie du site, du climat, etc. La prévision du potentiel de gonflement des sols est possible moyennant certaines méthodes empiriques basées sur des paramètres d'identification tels que la plasticité et la granulométrie déterminées lors des campagnes de reconnaissance. Une fois le caractère de gonflement pressenti dans la phase de reconnaissance préliminaire, une estimation de l'amplitude et de la pression de gonflement peut être établie à partir des corrélations, qui tendent à mettre en relation les paramètres de gonflement avec les paramètres géotechniques issus des essais d'identification. C'est dans cet aspect que s'inscrit cet article en traitant le cas d'un site algérien. Les résultats obtenus montrent une concordance entre les méthodes empiriques appliquées. Ces résultats sont aussi comparés avec ceux obtenus des essais de gonflement à l'oedométrique. L'évolution de la structure argileuse au cours de retraitgonflement est suivie dans l'objectif de comprendre le mécanisme de gonflement. Mots clés :Argiles gonflantes, identification, prévision, estimation, évolution de gonflement.Abstract. The clayey material hard and brittle when dry, presents the particularity of changing its consistence as a function of its water content. A certain percentage of moisture may transformed it into a plastic and manageable material. Depending on the particular structure of clay minerals, these modifications of consistence may be accompanied by more or less substantial volume variations, manifested, either, as a sharp increase of volume (swelling phenomenon) when the water content increases or shrinkage (shrinkage phenomenon) in period of marked rainfall. This behavior is essentially linked to some of environmental parameters of these soils, for example: the geology and lithology of the site, the climate, etc. The prediction of swelling potential of soil is possible with empirical methods that based on identification parameters, such as plasticity and particle size, determined during the reconnaissance campaigns. Once the character of the swelling sensed in preliminary recognition phase, an estimate of the amplitude and the pressure of swelling can be established by correlations that tend to link the swelling parameters with geotechnical parameters obtained from ...

The shrinking and swelling is a very common phenomenon in the world, mainly in arid and semiarid areas. The construction on these soils often requires a study of the risk of swelling, in advance. The emergence of this phenomenon in soils is caused primarily by the presence of swelling clays and water. The risk is most significant when the rate of the expansive minerals, such as bentonite, is important. Several researchers have studied the relationship between the percentages of swelling minerals and soil swelling potential. The researchers have shown the difficulty of characterization, because of the complexity of the phenomenon under natural conditions, where several other phenomena occur, and which are not considered in laboratory experimentation. This article addresses the characterization of several soils, with different swelling rates from the physical, chemical and mechanical tests. It shows the relationship between the quantity of swelling minerals and some site conditions, such as water content and consolidation stress, on the ability of soil to swell. This work aims to establish empirical relationships between the percentage of swelling minerals and soil swelling potential.

The Neogene basins are well known for their high susceptibility to landslides. This feature is mainly favoured by the lithological nature of the filling materials and slope morphology. This study proposes a combined frequency ratio and limits equilibrium methodology to perform a regional analysis of slope stability in the Neogene basin of Aomar Ben Haroun (Bouira, Algeria). For this purpose, different work steps have been conducted. Initially, the field site selection was made according to the surface geology underlying ground motion and the extent of landslide events. Subsequently, the landslide survey was built on existing studies and on high-resolution aerial photography and satellite imagery analysis, as well as on detailed fieldwork involving mapping and compilation of triggering factors. Besides, the evaluation of the landslide susceptibility around the study area was performed using the frequency ratio (FR) in the GIS environment. Note that the geotechnical characterization of each formation was determined from the physical and mechanical parameters of recent and old geotechnical studies carried out in the region. Moreover, the determination of the​​ landslide-prone areas with a characteristic stability factor for each slope was then computed using a two-dimensional limit equilibrium model. Thanks to the provided results, the classes of slopes that are characterized by parting surfaces susceptible to landslides are clearly defined. The result maps of the Aomar Miocene basin were categorized into low, moderate and high susceptibility classes. We have then been able to validate the obtained results by each used method. In the case of the inventory and susceptibility maps, we have also compared the two results based on the results of the area under the curve (AUC). For the frequency ratio (FR) and Limit Equilibrium (LE) models, the AUC are (83.23%) and (89.25%) respectively, which are indicating good and very good accuracy in the identification of landslide susceptibility zones of a basin and can be used in land use planning. In conclusion, this methodology highlights the fact that the landslides susceptibility map, which is obtained using the limit equilibrium model, was significantly more reliable and consistent than the susceptibility map completed by the frequency ratio model after field verification.

Views the scarcity of building sites, the urban development on soils with problems such as swelling soils, causes the damage to lightweight structures, as a sewerage networks, shod, etc. These damages are often classified in the low risk category. However, the neglect of these disorders can create geotechnical problems, much more complicated, with high risk, as a land motion. This case of disorders has been recording in several regions in Algeria, as example: Ain Defla, Boumerdes, and Medea, which is the studied case in this paper. The geotechnical study and the swelling tests on undisturbed and remolded samples, indicate the presence of a high swelling clay layer, of about 3-4 m deep. This research focuses on the evolution of the phenomenon of shrinking and swelling under the effect of a set of parameters existing in situ, such as climate cycles (alternating between winter and summer) and the effect of soil saturation mode. In this work, two modes are studied: saturation by infiltration and saturation by capillary. The results analysis shows the remolding of samples structure and the loss of their initial mechanical and physical properties. The test results justify the observed disorder on the site such as the erosion of foundation soils under the effect of the flow of surface water, and landslide triggering, affecting the whole of the site, and endanger the university campus located on this site.