Contribution à l’étude du mouvement de terrain de la ville de Tigzirt (Algérie)

This article is a contribution to the study of the causes, characterization, and numerical modeling, using finite elements, of the landslide affecting the coastal slope at the edge of the Mediterranean Sea near the city center of Tigzirt (Algeria). This slope is characterized by a relatively low inclination (13°–15°) and composed of two main geological formations (marly bedrock overlain by recent Quaternary deposits). Several factors have acted jointly and explain the activity of Tigzirt landslide: it is the effect of geological, morphological, and hydrogeological site contexts combined to triggering factors of various origins (human, climatic, and seismic). The landslide is characterized by a planar failure surface, which involves a global translational deformation towards the sea.     

Propriétés géotechniques de quelques formations géologiques propices aux glissements de terrains dans l'agglomération de Constantine (Algérie)

Résumé L'étude présentée se compose de deux parties. La première explique certaines formes de glissement de terrain observées dans l'agglomération de Constantine comme témoins d'une activité néotectonique. La seconde partie présente quelques caractéristiques géotechniques, des formations géologiques instables, obtenues par différents moyens: les essais de laboratoire, les essais in-situ, les corrélations. Received: 12 December 1997 · Accepted: 13 July 1998     

Exploitation piscicole du barrage Guenitra (Oum Toub,Skikda, Algérie)

The breeding of the carp Cyprinus carpio L. in the Guenitra dam (Oum, Toub, Skikda, Algeria) began in 1989 with 800 larvae imported from Hungary. This pilot project in carp breeding aimed to provide a stock of protein resource at low cost, with the purpose of extending the scheme to other water bodies in the area. Studies of the dam and its fauna took place between 1995 and 1999. It was determined that the Guenitra dam is favourable to carp breeding. The experiment can be replicated with success in similar water bodies.

L’élevage de la carpe Cyprinus carpio L. dans le barrage Guenitra (Skikda, Algérie) a vu le jour en 1989 avec l’ensemencement de 800 alevins importés de la Hongrie. Ce projet pilote de carpiculture avait pour objectif la mise en place d’une ressource protéique à moindre coÛt avec l’ambition de sa généralisation à d’autres plans d’eau de la région. Pour cela, nous avons étudié entre 1995 et 1999, l’hydrobiologie du barrage et les réactions biotope‐biocénose‐ichthyofaune en estimant le stock de pêche s’évaluant entre : Carpe grosse tête Ctenopharyngodon idella Val., Carpe herbivore Aristichthys nobilis R et Carpe argentée Hypophtalmichthys molitrix Val. Les résultats obtenus, durant ces trois campagnes (1996/97, 97/98 et 98/99) englobent les paramètres climatologiques, les analyses physico‐chimiques in situ des sels minéraux et en laboratoire et enfin, l’âge et la biométrie des trois espèces de Carpes. Cette étude diagnostic préliminaire montre que le barrage Guenitra est un écosystème tout à fait favorable à la mise en place et l’exploitation d’une activité carpicole. D’autre part, elle permet de consolider l’idée de transfert de ce type d’élevage dans d’autres retenues d’eau ayant un environnement similaire.     

Étude Rétro-analytique du glissement du bord Nord de la mine à ciel ouvert de Kef Essenoun (Djebel Onk), Algérie

On September 8th 2007, a few minutes before sunrise, a spectacular event occurred in the phosphate kef Essenoun open pit mine related to the mining field of Jebel Onk, located in Northeastern part of Algeria. It is a major landslide by volume (7–8 million m³) which had completely filled the pit of the mine and led to the temporary cessation of mining work over an extended period. This paper, presents a retro-analysis of this phenomenon for which, we draw the morphological, geological, hydro-geological and geotechnical characteristics of the deposit and the principal factors liable to be the triggering factors of this landslide.     

Caractérisation minéralogique et géotechnique des argiles marneuses gonflantes de la région de Médéa,Algérie

This paper presents the approach followed for the geological, mineralogical, and geotechnical characterization of swelling marly clays in the Médéa region. This investigation is conducted in order to estimate the swelling potential of this marly clay layer. The studied sites, located at about 80 km south of Algiers, Algeria, cover an area of approximatively 400 hectares. Five sites are considered. In the first step, the geological, tectonic, climatic, and hydrological contexts of the region are described. According to the geological map of Médéa, most of the formations encountered in the area are composed of Miocene layers represented by marly clays (Fig. 2). This region is characterized by its high and low temperature in summer and winter, respectively, and variable humidity (Fig. 3). In a second step, the results of geotechnical studies, X-ray diffraction tests, chemical analyses, and scanning electron microscope (SEM) observations are presented (Figs. 3, 4, 5, 6, 7, 8, 9). The soils contain quartz (20–26 %), calcium carbonates (11–55 %), kaolinite (8–13 %), illite (6–14 %) and Montmorillonite (18–26 %). The study of their microstructure by means of SEM indicates that these soils are formed by a compact marly clay matrix that is relatively homogeneous and oriented in the dip direction of bedding. A grain size analysis shows that the clay content varies between 17 and 70 %. The water content of all samples varies between 8 and 30 %. The values of the liquidity limit (LL) and plasticity index (PI) vary between 28–76 % and 16–36 % respectively, indicating a highly plastic soil; this is also confirmed by a specific surface varying between 99 and 179 m²/g. The dry density γ _d varies between 15 and 19 kN/m³. The swelling potential of the marly clay samples is evaluated firstly using various indirect methods. In literature, a number of empirical classifications are proposed by different authors (BRE 1980; Chen 1988; Komornik and David 1969; Seed et al. 1962; Snethen 1984; Vijayvergiya et Ghazzaly 1973 et Williams and Donaldson 1980). The swelling potential is related to certain physical properties of soils, such as consistency limits, clay content, methylene blue value, etc. In general, these methods indicate that all the tested soils have a high swelling potential, which confirms the results of mineralogical analysis. Secondly, direct measurements of swelling parameters are performed. Swelling tests are carried out using a standard slaved one-dimensional odometer using two methods: free swell and constant volume, according to standard ASTM D 4546-90 and AFNOR (1995). The swell pressure, the swell percentage and the swell index are given in Fig. 16. It is noted that the soils develop very significant swell pressures which vary between 25 and 900 kPa. This is in agreement with the results obtained by empirical methods. This investigation clearly shows that the marly clays of the Médéa region have a high swelling potential. Therefore, taking into account the phenomenon of soil swelling in structure design is essential.     

Cartographie des zones de risque de feux de forêt dans la commune de Doui Thabet,Saïda,Algérie

Forest fires have become a supremely topical subject and the year 2017 is considered to be exceptional in terms of burned areas. Thus, nationally more than 32,000 Ha have been ravaged by the flames, but above all, there has been a loss of life. The objective of this study is to implement a methodological approach for the mapping of forest fire risk areas. A model integrating GIS and remote sensing is used. It is based on the evaluation of several parameters that influence the initiation and propagation of a forest fire. These are vegetation, topography and anthropogenic factors. Imagery from the new SENTINEL2 satellite is used for vegetation mapping. GIS is use for the capture, processing, analysis and rendering of various images and maps. An application was carried out on the forest area of Doui Thabet (Saida/Algeria), often the target of fires. This study has two objectives. The first is to provide documents for potential users to help them in their planning and decision-making studies. The second objective is to provide managers with a tool that has made further progress in the management of geographic information.     

Valorisation de nouveaux matériaux naturels et recyclés dans la construction routière en Algérie

These recent years, the development of the civil engineering and especially the public works sectors in Algeria requires large amount of aggregates. Therefore, the abusive uncontrolled extraction of materials send out distress signals on the over-exploitation and reduction of the usual natural sources of aggregates, particularly alluvial deposits. Indeed, this can certainly maximize the risks of environmental contamination and threaten the aggregates supply continuity of projects, therefore seriously disturbing the development of the public work sector. For those reasons, the exploitation of new aggregates sources and the search for new local materials (natural or recycled materials) are urgently needed and seem to be a promising solution for sustainable development. Indeed, many natural materials such as (schist, marl,…) have been investigated in this area, given their availability and ease of extraction. Also, tons of inert wastes (concrete debris, glass debris,…) are generated from various human activities and abandoned in nature (along the roads) or buried in landfills where they surely represent contamination threats to ground water, while, these materials can be recovered and reused as alternative aggregates in important industrial sectors such as civil engineering and public works. The present experimental study is conducted in this context. It aims at valorizing local natural materials (marl) and recycled materials (glass debris) in road construction. Indeed, marl is among the most available materials in Algeria, it represents over 40% of the soils of Great Kabylia (Tizi-Ouzou). It is close to the surface (accessibility), with thicknesses exceeding 1000 meters (availability). Glass debris are also among the most available types of wastes (found in dumps and landfills). It is widely used in many industrial activities such as packaging, decoration, construction, and therefore it generates a lot of inert waste which take about 5000 years to decompose. For those reasons (large amounts and lengthy decomposition), several studies have been carried out for the glass possible reuse in civil engineering, especially in concrete and roads. To achieve this work, samples are prepared in the form of mixtures of marl with different proportions of glass debris (0, 10, 20, 30 and 40%). They are then submitted after identification to the main mechanical road tests, namely: compaction with modified Proctor tests in order to assess their maximal dry density, penetration with CBR tests (California Bearing Ratio) to evaluate puncture strength immediately under the circulation of vehicles during the construction of pavements or after soaking under water for 4 days (96 h), representing the worst humidity conditions on construction site. The samples are then subjected to direct shear tests using Casagrande shear box to assess their shear strength under traffic, especially during acceleration and braking of heavy vehicles. Finally, they are subjected to fragmentability, degradability, Los Angeles and micro-Deval tests to evaluate the evolution of the grains under different mechanical efforts (traffic, climatic and hydro-geological conditions). The experiments carried out have shown very remarkable results. Unlike the unfavorable behavior showed by the marl or the glass alone; their combination as mixtures presents very interesting mechanical characteristics under the different tests. Particularly, the mixtures with 20% of glass debris have shown the best aptitude to compaction, at low water content, and a high penetration strength in soaked and un-soaked conditions. In addition, it exhibits very interesting mechanical characteristics at shearing, with acceptable fragmentability, degradability, impact and wear behaviors. These results are very valuable and fully satisfy the requirements of standards for materials used in roads under weak and medium traffic. However, to better understand and develop the use of the studied materials in the road construction; further tests are necessary, such as long-term tests under cyclic natural loading (temperature, freeze–thaw,…). This research work may have considerable interests, both on the economical aspect and on the environmental impact in the region, mainly:

• Conservation of alluvial deposits and exploitation of new sources of aggregates to ensure the projects supply.
• Preservation of the environment by recovering abandoned glass wastes in nature, consequently, allowing the recovering of important storage spaces and significantly reducing the needs for new landfills.
• Contribution to the development of the recycling industries and the creation of more employment opportunities for the local population, leading to income generation and poverty reduction in developing countries such as Algeria, which offers a fertile field of recyclable materials (concrete, plastic, glass,…).

However, this study must be accompanied by appropriate and selective dumps installation strategies, with a large sensitizing of population in order to allow the easy collection of glass debris and other materials that can be recycled in the civil engineering field and other construction fields.

     

Stabilisation des sols gonflants: cas d'une argile en provenance de Mila (Algérie)

The construction of highways using swelling materials causes problems in many countries of the world. A number of authors have studied this subject, but the treatment of swelling clay remains a problem. This paper describes the problems associated with the black cotton soil in Algeria. It is hoped that it will help designers and contractors when making decisions in countries with similar soils and climate. A new apparatus capable of measuring swelling to a volume change of less than 10^–4 was used. Due to the difficulty of dealing with black cotton soils, these materials are frequently discarded as unusable for engineering works because of their sensitivity to water and their swelling potential. Mixing the black cotton soil with slake lime or another admixture has been found to modify the physical and chemical characteristics of the soil such that a significant decrease in swelling is observed and the material can be used in certain situations. The cationic exchange capacity (CEC) is modified by the addition of lime and the time of storage, while the swelling potential is significantly affected by the addition of 6% lime, even within a 7-day period. The influence of time is clearly shown. In both cases, 3% additive was mixed with the Mila clay. Using the first method the swelling potential dropped from 6% to less than 1% over a period of between 7 and 90?days, while using the second mode of storage over the same time span, the swelling potential dropped from 0.35% to less than 0.1%. The study demonstrates the method of storage, the percentage of mixed material added to the clay and time all have an important effect on the physical characteristics of the material, including the swelling potential.     

Quantification des matières en suspension et valorisation des sédiments de dragage à l’échelle d’un bassin semi-aride: Cas du barrage du K’sob (Algérie)

Due to the semi-arid climate, scarcity of vegetation, the presence of a sometimes steep slope, Algeria is vulnerable to soil erosion that threatens its socio-economic development. In the watershed of K’sob, transport of suspended sediment by rivers is a disturbing phenomenon due to siltation to 80 % of the dam at the outlet. Data of suspended sediment concentrations are closely related to liquid discharge (Q). Models of solid discharge (Q_s) according to the equation Q_s = aQ^b were used to perform qualitative and quantitative analysis of suspended sediment. Different scales of analysis helped identify and explain conclusively seasonal models. Sediment production is very high in the fall. In the spring, despite the increase in discharge, it is less significant. In summer, during a period of disappearance of vegetation cover, highly loaded floods are sometimes observed. Currently, millions of cubic meters of sediments are dredged each year. This large volume is an economic, environmental and ecological problem. To remedy this, an experimental study of manufacturing brick has been proposed with 65 % of sediment, 25 % of dune sand used as an additive and 10 % water. The shrinkage is minimal for a solid brick fabricated to 800 °C during 6 h of cooking. The mechanical tests carried out on the brick exhibit acceptable values of compression strength, mass density and water absorption. The study of the evolution of these parameters for different pressing intensities (13.2–20–30 and 40 kN) at different ages (4, 14, 21, and 28 days) shows that the solid brick acquires its resistance only after 21 days.     

Les pompes de chaleur manquent encore d'intérêt du point de vue coût

Lors d'une réunion ayant eu lieu il y a quelques mois, un sous-groupe technique de la commission de travail CIB W 67 sur la conservation de l'énergie a passé en revue les possibilités et les problémes des pompes de chaleur. La réunion a confirmé que les possibilités des pompes de chaleur sont considérables quant à la conservation de l'énergie et tous les pays sont tellement intéressés que le besoin d'une collaboration dans les recherches s'est intensifié.     

Instabilités gravitaires dans la région de Béjaïa (Algérie): Inventaire et appréciation de l’importance relative des différents paramètres conduisant au déclenchement,au maintien ou à l’activation des instabilités

Bulletin of Engineering Geology and the Environment - This article contributes to the analysis of the various factors that interact in triggering and reactivating of landslides in Béjaïa...     

Importance écologique et potentialité apicole à la périphérie du Parc national de Manda en zone soudanienne du Moyen-Chari (Tchad)

L’inventaire et les caractéristiques des plantes apicoles à la périphérie du Parc National de Manda (Tchad) ont été étudiés à travers des relevés floristiques, une analyse florale et des enquêtes ethnobotaniques effectués pendant la saison sèche de Décembre à Mars 2014. 78 espèces apicoles, appartenant à 35 familles ont été caractérisées. Les familles des Ceasalpiniaceae, Combretaceae et Mimosaceae représentaient respectivement 15.4; 10.3 et 10.3% de la flore apicole. Les ligneux étaient le type biologique fréquemment exploité par les abeilles. Vingt couleurs des fleurs ont été recensées, la couleur blanche (17.9%) étaient la plus sollicitée. La flore apicole autour de ce parc était majoritairement spontanée (79.4%). Pendant leur visite, les abeilles prélevaient essentiellement les grains de pollen, ce qui indiquerait leur contribution potentielle à la pollinisation. Aussi, ces abeilles étaient très sélectives avec seulement 12.8 des espèces intensément butinées, ce qui expliquerait la faible production du miel actuellement observée dans la région. Ces résultats montrent que la flore apicole autour du Parc se caractérise par une diversité spécifique appréciable mais un potentiel mellifère faiblement exploité. Les espèces préférées par les abeilles présenteraient un bon potentiel de domestication marqué par leur préservation dans les agrosystèmes. L’étude recommande leur domestication afin d’améliorer la productivité apicole et de diversifier la production des agrosystèmes autour de ce parc.     

Déformations gravitaires post glaciaires en terrains métamorphiques. Comparaison des indices de déformation du versant sud de la Toura (Saint-Christophe-en-Oisans, France) avec le phénomène de rupture interne du versant sud du Mont Sec (Séchilienne, France)

Introduction: The Sechilienne slope movement, near Grenoble, causes a majour risk and is intensively monitored since 1985. An original deformation mechanism has been proposed to explain the data. Some morphologicial similarities have been observed upstream on air photographs of the south slope of la Toura, naer Saint-Christophe-en-Oisans (France). The question is: is the same phenomenon occuring there too? The site of Saint-Chistophe-en-Oisans (France): The site is located in the Vénéon valley, 13?km upstream from Bourg d'Oisans (Fig.?1), under the Pointe de la Toura peak. There is no permanent stream flowing down the slope. The slope is constituted of gneiss of different formations separeted by North-South faults (Fig.?2). The foot of the slope is covered by alluvial deposits. On the slope itself, there are some recent moraines. The average slope angle is 36° (Fig.?6), which is around 10° lower than the mean value of the valley. The slope is much steeper near the crest, which could correspond to the summit scarp of a slope movement. The middle part of the slope is marked by huge transversal cracks with up-facing scarps, alternating with vertical cliffs. The screes are stopped by the up-facing scarps and underline the cracks on air photographs (Fig.?4). The geological structure is dominated by?(Fig.?5): –?north-south fractures corresponding to the main faults and to the foliation; –?hectometric cracks dipping of 65° in direction NE (N60). They show up-facing scarps and determine tilted-looking rock domains, as seen on the side thanks to the cut made by the "Torrent du Diable" stream; –?two less persistent discontinuity families, one dipping 65° toward SE (N 245) and the other one vertical, in direction N 80. The opening of the transversal cracks, their upfacing scarps and their curvature in the central part of the slope suggests a tilting of the slices. This phenomenon could date from the end or from low-level periods of the Würm glacial age (80000 to 10000?yr B.P.) The manual monitoring of five cracks shows that the phenomenon is still slowly active: mean opening 2?mm in two years, maximum 5?mm (Fig.?7 and 8). Tectonic hypothesis (Fig.?9) may explain the genesis of the atypical transversal cracks and will be tested by geochronological studies (fission traces on apatites) and geodetic measurements. The "Internal Rupture" deformation mechanism: The movement of the south slope of Mont-Sec (Séchilienne, France), constituted by micaschists causes a major risk near Grenoble (rockslide, damming of the Romanche valley, floods...), and is monitored since 1985. The main observations are: a settlement near the crest with opening of local cracks, no localised disorders on foot of the slope, the opening of transversal continuous cracks (with up-facing scarps), and the low inclination of the displacement vectors, whose direction is normal to the continuous cracks. A 240?m long investigation gallery revealed the rotation of rigid blocks (up to 80?m large) with opening or shearing of the contact planes (Fig.?10). These data do not fit with classical translationnal mechanisms and indicate a strong structural control. The mean direction of the rock anisotropy is not favourable neither to a generalised toppling mechanism. Data have been modelled with two main continuous joint families issued from the simplified geological model (one is vertical and the other steeply dipping toward the valley). The computation with the distinct elements method (code UDEC) reveals two distinct zones (Fig.?11): the upper zone is settling and horizontally expanding by shearing of the two joints families while the lower zone is retaining it with a "block toppling like" flexion deformation. The simulation reveals a very deep zone of yielding joints (extending down to the valley level), stress accumulations at the foot of each "cliff" of the final topography and important internal stresses inside the blocks in the flexion zone. Combined with the fluctuation of hydraulic conditions, this subcritical state of stress can, at the geological scale of time, induce secondary fracture propagation. The progressive localisation of this time-defered non reversible damaging phenomenon can lead to global failure of the slope on a non predetermined rupture surface. Conclusion: The morphological and structural observation of the gneissic south slope of la Toura (Saint-Christophe-en-Oisans, France) has revealed so many similarities with the Séchilienne case that the proposed mechanism appears to fit here too. Pursuing the studies on this lowly active site where the observation conditions are excellent will help understanding and controlling more dangerous sites like Sechilienne. Moreover, this phenomenon seems to concern many metamorphic slopes of the Alps.     

Les formations plio-quaternaires de la région de Casablanca (Maroc): aspects sédimentologique et géotechnique

The Plio-Quaternary formations of the Casablanca area consist of a sequence of cross-bedded strata. They frequently begin with a lumachelle conglomerate occasionally associated with gravels and marine calcarenite. The marine deposits are overlain by yellow and grey dune sandstones, locally oxidized at depositional horizons. These dunal calcarenites have been extensively exploited and hence their sedimentological and geotechnical parameters have been determined from numerous samples taken from the quarries in the region. The sedimentological study results show that these generally homogeneous materials consist mainly of well-graded fine to coarse carbonate sands (98%) containing both bioclasts and calcareous cements. It is clear that at the time of deposition there was little detrital material, with the marine deposits formed mainly of shell debris. Study shows that the marine deposits underwent early lithification in a shallow marine environment which then continued in a continental environment by the movement of meteoric water. The marine deposits are well cemented. They have a low degree of dissolution but quite a high degree of recrystallization, notably towards the bottom of the individual horizons. The dunal deposits which underwent lithification in a continental environment are characterized by a very low cementation, mainly at point contact, a high dissolution and a weak recrystallization. The difference in diagenesis affects both the physical and mechanical features of these Plio-Quaternary calcarenites. From a geotechnical point of view, the consolidated marine and dunal deposits have a weak to medium compressive strength (502), a very weak resistance to shocks (453. 8.?Density and percentage CaCO₃. 9.?Compression resistance and percentage CaCO₃. In view of the graph relationships, it is possible to estimate the other parameters from the determination of a single physical or mechanical feature of the calcarenite. However, the sedimentological and petrographical analyses show that the following factors can be subject to quantitative variations: (1) the carbonate content; (2) the nature of the bioclastic elements; (3) the grain size of the detrital elements; (4) the cement percentage and its grain size; and (5) the importance of dissolution and the vacuum percentage. These factors control the physical and mechanical features of the Plio-Quaternary formations of the Casablanca area. As a consequence, it is suggested that when considering the sedimentological features and physical and mechanical characteristics of the Plio-Quaternary formations of the Casablanca area, the particular deposits must first be categorized into one of the four following facies: lumachelle; marine calcarenite; yellowish dunal calcarenite; or grey dunal calcarenite.     

Prévision de la résistance mécanique du ciment en 30 heures

Le développement considérable de I'Arabie saoudite a obligé les laboratoires d'essai des matériaux à faire de grands progrès en peu de temps. Dans cet article, les chercheurs du Laboratoire d'essai des matériaux de Riyad expliquent comment ils ont utilisé un procédé accéléré pour prévoir la résistance à la compression de différents ciments Portland après 30 heures. Les résultats obtenus concordent, en moyenne, à ± 5% près avec les résistances que donnent les méthodes traditionnelles de conservation dans I'eau.     

Diversité floristique des mares temporaires de la région d’Annaba (Nord-Est Algérien)

Nine wetlands in Annaba region (North East of Algeria) were the subject of floristic inventories during three years (2014–2016). We have revealed the presence of five types of temporary ponds in which Ranunculus aquatilis L is dominant. The studied flora is rich and diversified. It comprises 190 species and 143 genera belonging to 58 botanical families. These species were either strictly subservient to humid zones or transgressive from terrestrial environments. This flora is characterized by a big proportion of rare and / or threatened taxa (11.05%). The composition of global biological spectra shows the dominance of therophytes, with 99 taxa (52.11%). The majority of the listed species belong to the Mediterranean phytochronic species. Eighteen taxa belonged to the endemic category. The preservation of this exceptional biodiversity, threatened in the short term, urgently requires phytoecological studies and relevant protection measures.