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.     

Phylogenetic diversity of aqueous microorganisms separated after the advanced tertiary of tap water

The species composition of bacterial community of the drinking tap water and water samples taken at different purification stages of the water conditioning plant at an enterprise producing special drinks has been analyzed. This study involves the analysis of 16S rRNA gene sequences and the use of molecular biology methods based on the phylogenetic analysis. The following bacterial species were identified: Bacillus nanhaiensis, Brevibacterium frigoritolerans, and Lysinibacillus fusiformis. All the studied strains belong to phylum Firmicutes, class Bacilli representing Gram-positive microorganisms that are not pathogenic to human. The presence of the bacteria investigated in different habitats such as the drinking chlorinated water, in the presence of stress factors (arid climate, high or low temperatures, depleted soil, and the occurrence of disinfectants) indicates their ability to easily adapt to new living conditions expanding their habitat.     

Characterization of Flaring and Non-Flaring Container Filled Votive Candles

Authors were provided two sets of 24 exemplar candles. Of these, 24 were identified as the same that the provider had observed “flaring”. Fourier Transform Infrared Spectroscopy (FTIR) analysis of the material showed that the candles that did not flare were soy based wax and that those that did flare were petroleum based wax. Burning the candles showed that melted wax in some petroleum based candles was ignited by the wick flame and produced a pool fire inside the candles’ glass container. Based on measured mass loss rate and the heat of combustion of petroleum based wax, the calculated power output of a normal burning candle is ca. 30 W. When the liquid wax pool ignited, the output was ca. 230 W, with significant flame extension above the top edge of candle’s glass container. The FTIR analysis also showed that twelve of the petroleum based wax candles had a simple hydroxyl compound, likely an alcohol, peak that was not present in the second sample of one dozen petroleum based wax candles. Burn testing showed that the candles from the sample with hydroxyl ignite a pool fire after burning for 15 to 30 min; the second sample of petroleum based wax candles, those that did not have the hydroxyl compound, did not ignite a pool fire. This suggests that the hydroxyl compound reduces the flashpoint of the wax to an ignition temperature attained after burning the candle for tens of minutes. Once the hydroxyl compound petroleum based wax melts and reaches a temperature above its flashpoint/flame point, it vaporizes sufficiently to be ignited, with flame extension of 152 mm (6 in) or more above the wax pool. This flame extension or “flaring” represents a significant fire hazard in that it may ignite nearby combustibles or fracture the candle’s glass container and release burning wax.     

Local buckling of steel equal angle members with normal and high strengths

Steel angle sections have been widely accepted with the development of steel structures, and such members made by high strength steel (HSS) sections are also increasingly used in buildings and bridges, and especially in transmission towers and long span trusses. Compared to normal strength steels, HSS exhibits different mechanical properties, which can cause different local buckling behavior. A finite element analysis (FEA) was performed in this paper to investigate the local buckling of steel equal angle members with different strengths under axial compression, where the residual stresses and the initial geometric imperfections of specimens were accurately described. Through this work, the relationship of the ultimate local buckling stress of steel equal angle members under axial compression as a function of steel strength and width-to-thickness ratio was established. By comparing the FEA results with the international design specifications (ANSI/AISC 360-10 and Eurocode 3), a modified design formula was developed and corresponding design suggestions were proposed, to take into account the effects of steel strength.     

A technical basis for regional aggregates policies

The planning system in England and Wales, the scale of the aggregates industry, and problems due to high levels of demand for aggregates are briefly outlined. A planning policy initiative to solve the problems is described. The information base required for preparation of these Guidelines for Aggregates Provision in England and Wales, and the scope of research commissioned by the Department of the Environment in support of work on aggregates policy are reviewed.     

Double quarries—Grade and artificial hard aggregates

The article deals with an interesting quarry in NW Slovenia, Yugoslavia, which exploits two kinds of rock at the same time: quartz keratophyre at the bottom and dolomite at the top, both of them of mid-Triassic age. Both rocks are processed in the same screening plant as aggregates for bitumen and cement concretes. Explorations for quartz keratophyre with tuffs started in 1966 for wearing courses of motorways. As such rocks are relatively few in Slovenia, and also in Yugoslavia, high grade carbonate aggregates were also proposed for less exacting roads and for lower layers of motorways. In the meanwhile, also artificial aggregates made from basic slags from ironworks were investigated. Good quality was ascertained and confirmed by a survey in use on a road.     

Development of materials specifications and emplacement procedures for backfilling nuclear fuel waste vaults

Atomic Energy of Canada Limited and Ontario Hydro are conducting a research program to assess the environmental impact and safety of the concept of disposal of nuclear fuel waste in an underground vault in plutonic rock of the Canadian Shield. The Vault Sealing Program, one of the components of the Nuclear Fuel Waste Management Program, is concerned with the development of materials specifications and emplacement procedures for backfilling the vault. Backfilling materials would surround the nuclear waste containers and fill all vault openings to minimize leaching and movement of radionuclides. This paper presents the procedure followed to select candidate backfill materials, the integration of mathematical modelling studies and physical testing for the definition of materials specifications, and the principal elements of the recommended handling and emplacement systems.     

Sable-cendre volante: Influence de la nature du granulat

The evolution, at 20°C and 40°C, of unconfined compressive strength (R'_c) and of splitting tensile strength (S_t) has been studied for five “sand-lime-fly ash” mixtures. Those mixtures are very similar with respect to grading, volumic mix design (aggregate, binder, water) and state of compaction, but they differ in the nature of the 0/2 mm sand: natural or crushed silica, limestone, porphyry and LD-slag. According to the aggregate treated, strengths and cohesion at the same age vary in a ratio from one to about two, even at long term. This difference in behaviour has been assigned principally to three factors which are in decreasing weight:

- surface texture of particles: strengths increase with micro-roughness owing to better adhesion between sand and binder mixture (fly ash + lime),

- chemical nature of aggregate (“acid-base”, character): at 40°C and 20°C till about 50 days of age, its influence seems to be of minor importance in comparison with that of micro-roughness. Later on, at 20°C, its effects appear clearly by a much slower strength increase when the aggregate has a rather “acid” character (silica and porphyry),

- angularity of particle: the influence of crushing is rather of little weight.

The estimation of the angle of internal friction from the S_t/R'_c ratio must be regarded more as an evaluation of the particle-binder adhesion for bound granular material than as one of the angle itself.     

The extent and effects of mass wasting in Ghana

Mass wasting in most of its forms have been studied throughout Ghana. The studies covered extent, distribution, effect, and possible corrective measures of slope failures. The performance of a number of slopes have been monitored for long periods and results have served as a basis for re-examination of existing design criteria in Ghana. Back, analysis of one major failure has been performed to obtain velocity and reach of a landslide. From, damage to farms, timber and a road from landslide in one instance, a projection is made to obtain the economic significance of landslides in Ghana. From the mode of failure in one specific case a methodology for corrective measures has been proposed.     

Legislation and administration of inground waste disposal in new South Wales and Victoria,Australia

Legislation and administration of waste disposal is primarily a State and Local Government responsibility in Australia. The legal and environmental principles that form the base of present and possibly future legislation and administration are described. Some problems are discussed and in particular that of legal retro-responsibility for wastes. New South Wales and Victoria have different legislative and administrative systems. Both are complex with many overlapping Acts. The role of the recently implemented Environment Planning and Assessment Act (1979) on siting waste facilities in N.S.W. in discussed. Control of disposal in Victoria is decentralized whereas in N.S.W. management is focussed in the Metropolitan Waste Disposal Authority.     

Enhancement of fire protection with directional cooling spray nozzles by use of AFFF

This paper will describe the work done and results of the study to characterize various directional cooling spray nozzles when used with Aqueous Film Forming Foam (AFFF) Agents.     

Stabilization of maiduguri black cotton soils of Nigeria with sand

The Lake Chad Basin is an extensive Quaternary lacustrine deposit of black clay soils. Laboratory investigations show that this soil consists of abundant proportions of montmorillonite and generally poses a major problem for Civil Engineering construction due to high volume changes. Alternative soils or aggregates suitable for base construction are very difficult to obtain in these localities and hence soil stabilization is of great economic importance to the construction industry. Methods of stabilizing this soil include lime stabilization, cement stabilization, mechanical stabilization, or heat treatment. This paper is primarily concerned with sand stabilization because of the presence of large deposits of dune sands at these locations. The result indicates that sand stabilization shows promise for improving the value of black cotton clays in pavement construction and is the most economical of all the applicable methods. However the method is recommended only for improving the subgrade and as a sub-base.     

Estimating room flashover potential

Flashover is the ultimate event in a room fire signaling the final untenability for room occupants and greatly increased hazard to other building spaces. Despite this importance, hazard evaluations of furnishings and other common fuel loads have normally not been based on estimates of flashover potential. This paper considers a simple combustion model and examines available experimental data.     

Detection of rock material variation by sonic velocity zoning

Quality variations in a hydrothermally altered dolerite from North-East England can be related to changes in dry density, porosity and strength, and in the results of standard tests on aggregates. Alteration can be detected as colour changes across sawn slabs, and the different types of altered dolerite can be characterised in terms of the standard micropetrographic indices. Sonic velocities through a 32 mm slab show satisfactory linear relations to density, porosity and percentage of sound minerals. Contours of equal sonic velocities or travel times can be drawn on the face of the block and the resultant broad zonation corresponds satisfactorily with the hydrothermal zones established by colour variations and detailed micropetrographic analyses.     

Cyclic loading triaxial testing of crushed rubble and lava

This paper describes a laboratory investigation into the suitability of crushed rubble as a substitute for conventional road base materials. The rubble investigated was a mixture of crushed concrete and crushed bricks, whilst lava from the Eifel was chosen as a reference material. Standard highway engineering tests (Proctor, CBR) and durability tests (Los Angeles Abrasion, Slake Durability and the standardized Dutch crushing test) were performed to provide reference date with every-day engineering practice. Cyclic loading triaxial tests were performed on both materials. The resilient moduli were determined at various levels of confining stress and the cyclic deviator stress. The susceptibility to plastic strain development (rutting) of both materials was determined in triaxial tests with up to 10⁶ load applications. The degradation of the materials in the plastic strain tests was determined through sieve analyses prior to and after the tests.     

Quarry reclamation in the Lombardy plain,Italy

The hydrogeological and geotechnical problems involved in the reclamation of quarries in the Lombardy plain are put forward, and some general criteria to solve such problems are suggested. Subsoil lithology is essentially formed by alluvial, highly pervious, non-cohesive soils, the grain size generally decreasing from North to South; during the last decades, several large and deep excavations for exploitation of sandy and gravelly aggregates have been made, and the reclamation of quarry areas has not to be considered. From the hydrogeological point of view, quarries are differentiated depending to whether or not they reach groundwater level; moreover, instability problems due to quarry/river interactions are investigated. From the geotechnical point of view, the problems depend on the excavated soil, on the filling material and on land use; slope stability and correction, and bottom and lateral watertightness are of primary importance. As alternatives to geomembranes, semi-permeable, compacted soil and soil/bentonite layers can often be used to achieve a satisfactory watertightness.     

An unusual foundation for an arch dam in mauritania

Between the years of 1981 and 1983 a 45 metres high arch dam was constructed for irrigation purposes at the Gorgol-Noir, a tributary of the Senegal River, in the semi-desert zone of southern Mauritania (Sahel). North of the city of M'bout the Gorgol-Noir erodes through a range of Precambrian metamorphic quartz-schists, trending north to south. The paper describes the investigations—engineering geological and the rock mechanics—undertaken in the course of the design and construction of the dam. Of particular importance were cavities located on the valley sides, proved to be related to shale intercalations.     

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.