RésuméLes fondations superficielles sont largement utilisées dans le domaine de la construction. L'étude de leur stabilité en particulier vis-à-vis du poinçonnement constitue un aspect primordial dans le but de construire des fondations et des ouvrages plus fiables et économiques. Dans cet article, on propose une analyse semi-probabiliste de la stabilité des fondations superficielles vis-à-vis du poinçonnement à l'état ultime basée sur l'Eurocode 7. Cette nouvelle approche prend en considération le caractère aléatoire des paramètres d'influence (géométrie, sol, surcharge), notamment celui des paramètres de cisaillement du sol. Une comparaison de cette approche semi-probabiliste avec des approches conventionnelles nationales (approches déterministes) est effectuée pour différents cas de chargement et différents types de sol.Mots-clés : fondations superficielles, capacité portante, stabilité, Eurocode 7, probabilité de rupture, indice de fiabilité. Semi-probabilistic analysis of the bearing capacity of the shallow foundations AbstractThe shallow foundations, are largely used in the field of construction. The study of their stability in particular bearing capacity constitutes a fundamental aspect with an aim of building foundations and eyen works more reliable and economic. In this paper, we propose a semi-probabilistic analysis-of the bearing capacity of the shallow foundations at the ultimate state based on the hew Eurocode 7. This new approach takes into account the randomness of the parameters of influence (geometry, ground, loads), in particular of the soil strenght parameters. A comparison between this semi-probabilistic approach and conventional national approaches (deterministic approaches) is carried out for several Cases of loading and types of soil.

Ballasted columns are an interesting technique for improving compressible soils in situ. Their major advantages are to reduce compaction, increase the bearing capacity of soils, accelerate consolidation, and eliminate the risks of liquefaction during earthquakes. Thanks to these advantages, reinforcement processes are considerably developed in the field of geotechnical construction and this is on an international scale. Numerical modelling is a necessary and effective alternative for approaching the real behavior of soils reinforced by ballasted columns. The present work aims to change several parameters, being, among others, the number of columns, the rise of the water table, and the friction angle. With this in mind, a parametric study was carried out in order to determine the influence of certain parameters on the settlement results and observe their influence on the mechanical behavior of the soil using the Plaxis 2D calculation code. This study found that the correct choice was based on the number of columns, which is three, while the increase in groundwater level does not have a significant influence on the results.

The South of Algeria is known for these immense sand dunes, which cover part of its territory (Sahara). The main objective of this study is the recovery of sands dune and wood waste (sawdust). The latter, which constitutes a potential source of several environmental and economic problems. The objective of this present work is to characterize the physico-mechanical properties at a young age of a dune sand-based mortar lightened by wood waste and to examine the suitability of using it for various applications in the construction of buildings. The improvement of the characteristics of these sands, which essentially formed of sand untapped to date and with the sole aim of enhancing this national sand wealth. The formulation of the mixtures is based on the substitution of dune sand by sawdust, at different weight contents 0, 10, 20 and 30%. The quantity of cement is fixed at 450 g. The results obtained show firstly that the introduction of sawdust improves the characteristics of the mixture (grain size tends to be spread out, reduction in densities), and secondly the physico-mechanical characteristics, especially at 30% substitution (reduction absorption by total immersion of 20.50%, porosity of 28.32%, wet density of 1.73% and dry density of 14.94% and increase in tensile strength of 61.43% and in compression of 63.87%). The effect of sawdust on the relationships between the properties of mortars was clearly noted either for the relationships between early strengths or between compressive and tensile strengths.

In the geotechnical engineering field, shallow foundations are frequently needed to ensure good fieldwork stability. They are also intended to permanently and uniformly transmit all load pressure on the seating floor. However, numerous mechanical constraints, such as bearing capacity of foundations, durability, stability, design of shallow foundations, lead, unfortunately, to a serious realization challenge. Finding an adequate solution presents the main goal and effort of both scholars and professionals. Indeed, the corresponding drawback is observed through the high number of reported damages that occurred in the structure of foundations and the punching failure. The failure mechanisms of shallow foundations, verified in full size or on scale models, show “sliding surfaces” and rigid (solid) blocks, which can be described with the kinematic method of rigid solids. The main objective of this study is the application of the kinematic method of rigid solids in the study of the stability of shallow foundations with respect to punching, the purpose of which is to determine the bearing capacity factors Nc, N γ, and the passive earth pressure coefficient Kp of foundations. In this context, two mechanical models have been proposed with 5 and 7 rigid solids, and a program developed via the MathCAD environment is applied to check the validity of the two previous models. The kinematic method of rigid solids gives results very close and comparable with that of Caquot/Kerisel for the factors of the bearing capacity and passive earth pressure coefficient - the ratio Kp - according to the five- and seven-solid model.

The use of self-compacting concrete (SCC) has developed considerably in recent years, and much attention is paid to the study of their mechanical and rheological properties. The environment is a very important issue, and its preservation is a common responsibility, the wastes thrown by human beings compose a great danger on the environment, so it is necessary to encourage their elimination by recycling operation and their use as aggregates in the manufacture of self-compacting concrete. The study is based on the idea that the incorporation of rubber aggregates improves some behaviors of the SCC and enhances the use of waste, so the incorporation of aggregates in the composition of self-compacting concrete (SCC) has an interest that deserves to be studied. The objective of this work is to valorize the use of waste, especially used tires as rubber aggregates and also consists in studying the influence of the incorporation of these aggregates on the mechanical behavior of the self-compacting concrete. The dosages used in aggregates are of the order of 1 and 2% by weight of the concrete. This study will examine the role and influence of the rubber aggregate content on the characteristics of the SCC. The incorporation of these aggregates in the SCC is beneficial for the improvement of the ductility of the concrete material known for its brittleness in traction. The results of this work suggest that the pneumatic aggregates can be compared to other aggregates used as reinforcement in self-compacting concrete. They are completely suitable for use as reinforcement in self-compacting concrete.