saeed hejazirad

Study of foundation bearing capacity and slope stability has always been a common and practical issue in geotechnical engineering. The combination of these two problems in the presence of pore water pressure adds to the complexity of the problem. In the present study, the effect of pore water pressure on the three-dimensional stability of slopes under concentrated load or the bearing capacity of rectangular foundations located in the vicinity of slopes has been investigated. Then, using a circular rupture mechanism and generalization of the program, the problem is analyzed by the upper boundary limit analysis method, taking into account the pore water pressure in three dimensions. In this regard, with the expansion of the Rosas program as an infrastructure program, it has been able to consider the parameters related to water pressure. Considering that the effective variables, foundation and slope geometry, foundation distance from the sloping edge and soil strength parameters include adhesion and internal friction angle of the soil, the mentioned variables have been analyzed to calculate the bearing capacity of the foundation located on the slope. In the discussion of the bearing capacity of the foundation located on the slope, as the foundation moves away from the edge of the gable, the effect of increasing the pore water pressure on the reduction of the bearing capacity of the foundation also increases.

Excavating tunnels in soft urban land has its own limitations. One of the most important limitations is the control of surface settlements to prevent damage to surface structures. Accordingly, choosing the best method for tunnel excavation is very significant. Among the existing methods for digging urban tunnels, step drilling methods are very widely used. Typically, these methods are not comparable to the mechanized drilling method for long tunnels. However, step drilling methods are used to drill short tunnels, large sections such as subway stations, non-circular sections, and complex structures such as intersections. Among the most important executive parts of step drilling are the length of the drilling step and the distance between the work fronts. Although these two parameters are very influential factors on the technical and economic aspects of the step drilling method, but there is no coherent process to determine these two parameters. In this research, the drilling stages of the tunnel of line A of Qom metro have been investigated in order to determine the length of the drilling step and the distance between the work fronts. The method of excavating this tunnel is pre support method. Using three-dimensional finite element modeling (Praxis 3D Tunnel), tunnel drilling is simulated in different progress modes. Eight progressive modes are provided for step length and six modes for spacing between fronts. The length of the drilling step and the distance between the work fronts are selected by examining the effect of different forward modes on the transverse diagrams of surface settlement, settlement values and soil displacement around the tunnel. Studies show that the same drilling step of 1 meter for the upper and lower parts with a distance of 25 meters between the fronts (a distance of more than one diameter of the tunnel), has the best performance for tunneling.

Today explosion in urban centers and residential areas, there is a danger that threatens all buildings. Explosions inside or near a building can cause sudden damage to building frames. Analysis and design of structures under explosive loads requires a precise understanding of the dynamic response of members and systems of structures under this load.In this research, the behavior of three types of flexural joints of reduced type, end plate and reinforced with top and bottom plate in the phenomenon of explosion and progressive failure has been studied and to perform these studies and numerical simulation of ABAQUS finite element software And Etabs (V.NL13) were used.In determining the type of explosion, two parameters are usually decisive: the size of the weapon, which is equivalent to the weight of TNT, and the distance, which indicates the distance from the center of the explosive to the desired volume. In steel structures, there are two types of lateral load-bearing systems: flexural frame system and simple frame system with bracing. In the meantime, the bending joints of the beam to the column are the bridge of this partnership, and if it is destroyed, the structure can suffer a lot of damage. Due to the above explanations and the importance of flexural joints under lateral loads, in this research, flexural joints have been investigated.

Deep foundation are used to transfer loads of large and high rise building to subsurface layers that have sufficient strength. Piles are one of the most common deep foundations which are installed in the form of driven an bored for many years, the high noise and variation by the driving and the hardness and the limitations of the performance of the bored piles caused to use a new type of pile which installed to the soil using torque and a small amount of axial compressive load, Helical pile can be considered as such piles. Drilled displacement piles are another type of this piles. Due to the increasing use of these piles, there are still limit studies on them and there is a need to study their behaviour in different soils and conditions. Three models of piles in the laboratory section were implemented and loaded in FCV-AUT and compared with studies in the field. Compressive and tensile static load were performed according to ASTM D1143 and ASTM D3689 standard and rapid loading test.Drilled displacement pile in tensile and compressive performance was better than other torque driven pile. Because of concrete is cheaper than steel, these piles can be a good alternative for driven and bored pile in urban areas.