Many earth dams are damaged by shearing under seismic stresses effect. In Algeria, earthquake of 21 May 2003, of magnitude Mm = 6.9 on Richter scale, considered as the most violent for more than 20 years, occurred about 70 km east of Algiers’s capital, where a large number of structures were damaged in this region. The aim of this article is to present a numerical analysis of an earth dam in the province of Oum-Elboughi. The objective is to show the influence of compressive seismic waves and the effect of foundation deph on dam behavior .The stady was carried out using a 2D finite difference method (FDM) using the FLAC 2D calculation code. In this analysis, a soil nonlinear behaviour is provided by a combined Hardin/Drnevich hysteretic damping behaviour model with Mohr–Coulomb elasto-plastic model. Results that are presented in terms of deformations and shear stresses developed at the dam and dam foundation show that the most critical area is located on the downstream side of the dam. Increasing the foundation depth decreases the value of horizontal stress, while decreasing it increases the dam instability risk.

The stability of underground structures of great height in soft clays in urban areas requires a study which takes into account all the parameters which influence its behavior. The study of the Oued Smar—Algiers station which is carried out in an urban area is numerically analyzed in 3D. This analysis takes into account the effect of the environment of the structure, the geotechnical parameters, as well as the effect of the different implementation phases. The results obtained in terms of stresses and pore pressures are studied. Inclinometers installed in the wall according to a fixed grid, whose measurements taken after each excavation are compared with the displacements obtained numerically. The calculated horizontal displacements are lower than those measured in situ.

This research work is part of the trend of soil reinforcement procedures aimed at improving poor quality soils. Among these
techniques, those that use stone columns. Although the aspects concerning the construction processes are now well mastered,
the design methods of these reinforced soils remain to be developed.
A numerical simulation presented to study two unit cell models. The 3D proposed simulation model is subjected to gravity
and a static load. The first model presents a unit cell composed of stone column in the center and a surrounding clay soil
volume. The second is converted into an equivalent unit cell (the volume averaging) in terms of physical and mechanical
parameters of a composite material (equivalent parameters).
Under the effect of incrementally loading–unloading applied to these unit cell models, voids ratio variations and stress path
evolution are analyzed. The results indicate that applying a load to an equivalent unit cell can affect the void ratio-volumetric
deformation curves and increase settlement. The void ratio and the corresponding volumetric deformation decreased by
comparing the equivalent homogenized model with the non-homogenized model. The results show that the void ratio
decreases by about 10% on average, but the volumetric strain decreases by 80%. Therefore, the stress path corresponding
to the decrease of the average effective stress by 1% increases the deviatoric stress on average by 10%. Diagrams obtained
by numerical results are in accordance with the results derived from experimental observations. The adopted technique can
substantially can describe sufficiently the influence of the equivalents physical and mechanical parameters on the improvement
in the soil of unit cell.

When designing tunnels, it is advisable to pre-estimate several tunnel parameters such as the depth (cover), the lining thickness, and the shape of the tunnel cross section. This condition is important in order to limit deformations during construction of the tunnel, and to ensure good tunnel resistance under seismic load conditions. In this context, the present paper is devoted to the analysis of the influence of some test parameters (the cover of the tunnel, the thickness of the lining, and the shape of the tunnel and the direction of the seismic waves) on the behaviour of the soil and the lining of a shallow tunnel built in soft ground subjected to seismic loading. The reference model for this parametric study is a real case, which happens to be the tunnel of Djebel El Ouahch (EastWest motorway) in the province of Constantine/ Algeria. The study is performed in three dimensions (3D) using a finite difference calculation method based on the FLAC3D calculation code. The results are presented in terms of shear strain induced in the soil around the tunnel, surface settlement, and vertical displacement of soil under the raft foundation, and also shear stress, bending moment, and shear strain, induced in the tunnel lining. The results show that the increase in thickness of the lining causes a reduction in shear force, and shear strain, while the circular or oval shape of the tunnel cross section results in low values of strain in the lining and ground displacement. It has been also pointed out that bending moment and shear strain induced in the lining are relatively low in comparison with the other forms. On the other hand, the direction of the seismic waves has a great influence on the behaviour of the lining and the surrounding soil. These results demonstrate that the strongest and most stable tunnel is the deepest tunnel with circular or oval section with a large thickness of the tunnel lining under the effect of compressive seismic waves. The results of the present study will be useful in the design of such a case by understanding the effects of various influencing parameters that control the stability of the tunnel in soil with bad characteristics

The main purpose of this study was to compare and evaluate the performance of two multicriteria models for landslide susceptibility assessment in Constantine, north-east of Algeria. The landslide susceptibility maps were produced using the analytic hierarchy process (AHP) and Fuzzy AHP (FAHP) via twelve landslides conditioning factors, including the slope gradient, lithology, land cover, distance from drainage network, distance from the roads, distance from faults, topographic wetness index, stream power index, slope curvature, Normalized Difference Vegetation Index, slope aspect and elevation. In this study, the mentioned models were used to derive the weighting value of the conditioning factors. For the validation process of these models, the receiver operating characteristic analysis, and the area under the curve (AUC) were applied by comparing the obtained results to The landslide inventory map which prepared using the archives of scientific publications, reports of local authorities, and field survey as well as analyzing satellite imagery. According to the AUC values, the FAHP model had the highest value (0.908) followed by the AHP model (0.777). As a result, the FAHP model is more consistent and accurate than the AHP in this case study. The outcome of this paper may be useful for landslide susceptibility assessment and land use management.

The study of the seismic behavior of tunnels has become a major concern for geotechnicians in recent years, especially after the collapse of the many underground structures around the world, constructed in soft ground at shallow depths. Several studies focused on the distortion of the tunnel cross section caused by shear waves which propagate vertically to the tunnel axis. However, the study of the tunnel seismic response to the compression waves which propagate parallel to the axis of the tunnel is almost neglected. These compression waves can cause a serious axial and bending deformation in the tunnel lining. Therefore, this paper aims to present a numerical analysis of part of the T1 tunnel of the Algerian East-West Highway, in the province of Constantine, that suffered a very significant damage caused by a sudden collapse. The goal is to demonstrate the influence of seismic waves of compression as well …