فهرست مطالب moein mohammadizadeh

The bearing capacity and settlement of shallow foundations located on the pipe are usually not acceptable in sandy soils. Therefore, in order to improve the performance of strip foundations, various methods are proposed, as a cost-effective alternative is to add skirts to the edges of the shallow foundation. the addition of the skirt to the edges of the shallow foundation increases the effective depth of the foundation and soil trapped within the skirts, and loads of the structure are transferred to the bottom depth at the level of the skirt tip. In recent years, performance assessment of skirted foundations has become one of the desired topics for civil engineers. In this article, the effect of the burial depth and horizontal distance from the center of the pipe to a single load have been evaluated using numerical and experimental tests. Therefore, the skirted foundations located on the buried pipe with skirts B and 2B (B is the width of the foundation) have been used. The results of the laboratory tests show that by using the skirted foundation with skirts of 2B, the bearing capacity can be increased by more than 300% compared to the strip foundation. A numerical comparison of the skirted foundation with semi-deep and embedded strip foundation shows that the bearing capacity of the skirted foundation was less than 10% different from the semi-deep foundation. Civil engineers can be led towards more economical and accurate designs by using the skirted foundation.

Analysis of underground structures under blast has challenges due to the complexity of blast dynamic loading and soil behavior. Due to the role of underground structures as a shelter and the vulnerability of these structures to explosive loads, it is vital to investigate and analyze the effect of explosions on these structures. The aim of this study is to investigate the effect of explosive projectile distance from the underground structure and the diameter of the explosive sphere on the underground structure. For this purpose, using the finite difference method and dynamic analysis, the underground structure was simulated for different distances of the explosive projectile and different diameters of the explosive sphere. In this study, the propagation of explosion waves in a spherical manner was considered by applying an explosion pressure on the wall of the explosive sphere. The results show that with increasing the distance of the underground structure from the center of the explosion, the maximum soil pressure on the maintenance system as well as the bending moment and axial force in the canopy and wall of the tunnel maintenance structure decrease exponentially. In addition, after the explosion wave reaches the tunnel maintenance system, the displacement and vertical velocity of the storage system particles in the tunnel crown is the highest. As the diameter of the explosive sphere increases, the bending moment at the crown and wall of the tunnel increases almost linearly, which is three times the slope for the tunnel crown