Purpose. To understand the effect of fissured material on tunnels. These infrastructure tunnels must be safe in all respects, including construction, materials, and more. One of the challenges which engineers face is the need to consider material types as well as fissured material. As a result, in order to ensure the safety of the tunnel, it is important for us to anticipate possible precipitation, displacements, stresses and strains caused by the construction of tunnels in fractured environments. Methodology. The OPTUMG2 software was used for thisnumerical study, the tunnel was modeled applying the hypothesis of two-dimensional plane deformation with the use of the finite element method, which is used to model continuous media. The Mohr-Coulomb criterium was considered to simulate the elastoplastic nonlinear behaviour of this model. Findings. The ndings demonstrate that the orientation of weakness planes can have a major impact on tunnel stability. Thus, it was observed that 45, and 60 for angle 1, and 110, and 135 for the second angle 2 present the most critical situations. The influence of fissured material (soil) on civil engineering projects such as tunneling should be taken into consideration. Originality. The tunnels stability is determined by the measuring of the displacement (settlement), stresses, and deformation, under the effect of the fissured material in the environment. In this paper we simulated a model with various crack angles. As for the orientation of plane, for the angl3e 1 the values are changed to 0, 20, 45, 65, and 90, the second angle 2 was changed from 110, 135, 155, 175, to 180. Practical value. The number of tunnels and infrastructure projects is constantly increasing. This is because they are important for the development of countries and for accelerating economic growth, shortening distances and travel time by linking urban areas that have natural obstacles such as mountains. We found that the orientation planes can have a major impact on tunnel stability. Thus, it was observed that 45, and 60 for first angle, and 110, and 135 for the second angle present the most critical situations.

Les bétons à hautes performances (BHP) sont des bétons qui présentent des résistances mécaniques élevées (> 60 MPa) et une micro texture très dense (faible porosité), qui empêche la pénétration des agents agressifs. Dans le contexte de ce travail une étude expérimentale a été faite à fin d’élaborer un béton BHP à base des matériaux locaux disponible dans la région de Béchar, dont le but de réduire le cout de BHP. Le deuxième objectif de ce travail est de voir l’influence du rapport E/C (0.3, 0.35, 0.4) sur le comportement rhéologique et physico-mécanique (la maniabilité, porosité, résistances à la compression, résistance à la flexion, l’absorption d’eau et la masse volumique) de BHP élaboré à base de pouzzolane naturelle de la région de Boukais (Bechar), et voir aussi l’effet de la pouzzolane naturelle qui a utilisé comme une substitution partielle dans le ciment portland (10% et 20%) sur le comportement physico-mécanique de BHP.

Geological discontinuities such as faults and shear joints present significant challenges in slope stability assessments, often altering failure mechanisms and reducing safety margins. This study explores the influence of fault geometry on slope stability through a comprehensive numerical investigation using finite element limit analysis with upper and lower bound formulations. A series of parametric simulations were conducted on a 17-meter-high slope model, incorporating faults of varying lengths (3.75 to 21.5 meters) positioned at different distances from the slope face. The fault-free slope exhibited stable conditions, with safety factors ranging from 1.889 to 1.923 and circular failure surfaces. In contrast, the introduction of faults in close proximity to the slope resulted in marked reductions in stability. The most critical scenario, involving a 21.5-meter fault located 1 meter from the slope, yielded safety factors as low as 0.675–0.693 and a transition in failure mode from circular to planar sliding. Results reveal that fault proximity has a more pronounced impact on slope behavior than fault length. Faults situated beyond 4 meters from the slope face exhibited negligible influence on stability, whereas those within the near-field zone induced safety factor reductions exceeding 60%. These findings provide actionable insights for geotechnical design, emphasizing the necessity of detailed fault mapping within critical slope zones. The study contributes to the development of more reliable, risk-informed approaches to slope stability analysis in structurally complex terrains.

The world is widely exposed to risks related to the presence of underground cavities, whether natural or linked to human activities. These cavities represent a potential risk of collapse and thus of danger, particularly in urban areas. This article aims to explore through numerical modeling the effect of the mechanical characteristics of the soil on the instability of the underground cavity. Subsequently, a parametric study was conducted to study the influence of certain factors, including the relative distance between the foundation and the cavity and the influence of the size of the cavity on the ground. The studies will be carried out after a calculation by the finite element method.