Effect of Anisotropy and Destructuration on the Behavior of Murro Test Embankment

This paper investigates the influence of anisotropy and destructuration on the behavior of a test embankment on soft clay. The test embankment at Murro, Finland, was commissioned in 1993 by the Finnish Road Administration and has been monitored for over 10?years. The construction and consolidation of Murro test embankment is analyzed with finite element method using three different constitutive models to represent the soft soil. The results are compared with field observations. The constitutive models used include two recently proposed constitutive models, namely S-CLAY1 that accounts for initial and plastic strain induced anisotropy and its extension, called S-CLAY1S. The S-CLAY1S model accounts, additionally, for interparticle bonding and degradation of bonds. For comparison, the test embankment is also analyzed using the isotropic Modified Cam Clay model. The simulations demonstrate that for this type of problem, it is important to account for the anisotropy, whereas destructuration appears to have less influence on predicted deformations. However, only a model incorporating destructuration can explain the decrease in undrained shear strength during consolidation that was measured in field.     

Numerical Investigation of Forced Convection Nonequilibrium Effects on Heat and Mass Transfer in Porous Media

A numerical investigation is performed to analyze the coupled heat and mass transfer in porous media with a strong exothermic reaction. Similar problems have received great attention due to their relevance in a wide variety of engineering applications, such as heat pipes, drying technologies, nuclear reactors, catalytic reactors, environmentally clean utilization of energy, and many others. The momentum transfer in the porous substrate is modeled with the Darcy–Brinkman–Forchheimer law, while the temperature and concentration fields are obtained subsequently from the energy and diffusion equations. The considered configuration consists of a cylindrical duct where a first-order reaction is supposed to occur. The governing equations are solved by using the finite-volume method. The SIMPLER algorithm is applied to solve the momentum and continuity equations. The power-law scheme is used to model the interaction between convection and diffusion terms. The effect of the main governing parameters, such as permeability, aspect ratio, solid-to-fluid conductivity ratio, Reynolds number, Biot number, and the modified Frank-Kamenetskii number, are studied. The comparison with previously published work shows excellent agreement.     

Use of Endostemon tereticaulis (Pear.) M.Ashby and Hyptis spicigera Lam. Plant Extracts as Corrosion Green Inhibitors for Mild Steel in 1M HCl: Electrochemical and Surface Morphological Studies

Protection of Metals and Physical Chemistry of Surfaces - In the present study, we evaluated the effect of corrosion inhibition of ethanol extracts from Endostemon tereticaulis and Hyptis spicigera...     

Structure, infrared and Raman spectroscopic studies of new Sr0.50SbFe(PO4)3 and SrSb0.50Fe1.50(PO4)3 Nasicon phases

Two newly synthesised Sr_0.50SbFe(PO₄)₃ [Sr_0.5.] and SrSb_0.50Fe_1.50(PO₄)₃ [Sr.] phases were obtained by conventional solid-state reaction techniques at 1000 °C in air atmosphere. Their crystallographic structures were determined at room temperature from X-ray powder diffraction (XRPD) data using the Rietveld analysis. Both compounds belong to the Nasicon structural family. [Sr_0.5.] and [Sr.] crystallise in rhombohedral system with \textR[`3] {\text{R}}\overline{3} and \textR[`3] \textc {\text{R}}\overline{3} {\text{c}} space group, respectively. Hexagonal cell parameters for [Sr_0.5.] and [Sr.] are: a = 8.227(1) ?, c = 22.767(2) ? and a = 8.339(1) ?, c = 22.704(2) ?, respectively. Sr²⁺ and vacancies in {[Sr_0.50]_3a[□_0.50]_3b}_M1SbFe(PO₄)₃ are practically ordered within the two positions, 3a and 3b, of M1 sites. Structure refinements show also an ordered distribution of Sb⁵⁺ and Fe³⁺ ions within the Nasicon framework. Within the structure, each Sr_(3a)O₆ octahedron shares two faces with two Fe³⁺O₆ octahedra and each vacancy (□_(3b)O₆) site is located between two Sb⁵⁺O₆ octahedra. In [Sr]_M1Sb_0.50Fe_1.50(PO₄)₃ compound, all M1 sites are occupied by Sr²⁺ and the Sb⁵⁺ and Fe³⁺ ions are randomly distributed within the Nasicon framework. A Raman and infrared spectroscopic study was used to obtain further structural information about the nature of bonding in both selected compositions.     

Methodology for WEEE assessment in Algeria

Waste electrical and electronic equipment (WEEE) generated in emerging countries is increasing. This study presents a methodology to improve assessment and monitoring WEEE in Algeria. The proposed methodology is a two-step approach. The first step is the collection and collation of existing data from different national and international sources. In the second step, different assessment and forecasting methods are applied. Forecasting methods were selected from those models which provided minimum error indices. The paper considers also the availability and reliability of data in order to provide a future reliable assessment of WEEE in Algeria. The study revealed that the forecasting methods do not have a big influence on the results contrary to the inputs of the model.     

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 glissements de terrain du quartier Bélouizdad, Constantine, Algérie

In Constantine, Belouizdad district landslides are extensive (Fig. 1). They occur along a hillside largely urbanized, and cover over 30 hectares. Dozens of houses were destroyed. The formations raised by these movements correspond to the alternating of thick Miocene clays and conglomerates. These contain several aquifers. The study of these landslides is conducted on the basis of recognition by deep boreholes equipped with piezometers and inclinometers. The inclinometric measurements have revealed failure surfaces sometimes deep (20 to 30 m) and north displacement, towards the Rhumel wadi. The use of a stability calculation software “Talren” shows on the one hand, the high sensitivity of unstable Miocene formations in the presence of water and on the other hand, a significant revival of the safety factor by reducing the pore pressure. The recommended solutions are therefore a lowering of underground water levels. Two techniques are recommended : deep drainage trench or galleries combined with radiating drainage holes.     

Coupling of electrodialysis and leaching processes for removing of cadmium from phosphate ore

Phosphate rock is a valuable material that is used for the production of large phosphorus chemicals. However, this natural material usually contains some toxic elements such as cadmium (Cd). Cd is a non-nutritive metal regarded as harmful to both humans and the environment. The main toxic effects of Cd on human health are the kidney and renal cortex diseases. Other effects were observed on pulmonary, cardiovascular, and musculoskeletal systems, in addition to including Cd as a human carcinogen. In order to reduce the cadmium content in the phosphate ore, an original method was studied and consists of coupling both leaching and electrodialysis. The effects of process parameters, such as reaction time, nature, and concentration of the extracting agent, liquid/phosphate ore ratio, pH, temperature, and current density, were investigated. The obtained results show that the cadmium extraction from phosphate ore using simple batch leaching does not reduce the cadmium content to the required level. However, the application of leaching- electrodialysis coupled method at optimum current density of 10 mA cm^?2 increases the cadmium extraction efficiency up to 84.3%. This synergetic process could be applied to the treatment of phosphate ore containing cadmium.