چكيده به لاتين
The role of local construction effects in intensifying ground tremors has been revealed for a long time. Among the things that have attracted the attention of many researchers in recent years is the effect of the presence of natural underground spaces such as caves and underground holes or man-made underground structures such as tunnels on the seismic response of the building, especially on the ground level. Although the importance of the presence of underground spaces and structures on the seismic response of the building and especially on the ground surface has been determined based on analytical, numerical and more or less laboratory studies, but even in laboratory modeling using models with different materials in each test, it is difficult. because there has been no research on the accuracy of simulation and the amount of error resulting from the modulus of elasticity of materials in tunnel modeling under seismic loading. The current research has investigated the effect of different types of tunnels in the model in investigating the effects of underground structures (tunnels) on the seismic response of the ground surface and tunnel stresses with the help of physical modeling with a seismic table. In this thesis, the effect of the material of the model with the same parallelization in the results of the magnification of the surface acceleration and also the tunnel stresses has been discussed. In the experiments conducted with the seismic table using the valid scale coefficients of the tunnel simulation, in the box with sandy soil, the effect of the different material of the tunnel in the model on the response of the ground surface and tunnel stresses has been investigated. In previous research, models with asbestos cement materials with 23 GPa modulus of elasticity, polyethylene with 1.1 GPa modulus of elasticity, aluminum with 69 GPa modulus of elasticity and glass (Plexiglass) with 2.1 GPa modulus of elasticity, results have been presented with a suitable analogy, in this thesis to investigate the effect of the material of the model in the same analogy in comparison with the model made of polyethylene with a modulus of elasticity 1.1 GPa and an inner diameter of 50 cm and a lining thickness of 2.9 cm, from a model made of steel and with Elasticity modulus 210 GPa, inner diameter 50 cm and lining thickness 0.5 cm were used. In order to compare the effect of different types of tunnel in the same comparison, the results of the model of this thesis, which was made of steel, were compared with the results of the research model of Baziar and Dehghani in 2021, which was made of polyethylene. As a result, according to the results, as expected, in the 0.1 g and 0.2 g accelerations, the acceleration from the bed towards the soil surface has been magnified, and due to the low frequency of the applied acceleration, we can see the low effect of the tunnel on the surface acceleration magnification. Also at acceleration 0.45 g witnessed the reduction of the acceleration magnification from the bed to the surface, and due to the higher applied frequency of this acceleration, the effect of the tunnel on the reduction of the surface acceleration magnification was well observed, which shows the greater effect of the applied frequency than the applied acceleration. At the 0.96 g acceleration, unlike other accelerations, we see a reduction in the acceleration from the bed to the soil surface, and also due to the increase in the applied acceleration and the stability of the applied frequency compared to the 0.1 g and 0.2 g accelerations, we can see the increase in the effect of the tunnel in increasing the reduction of the surface. will be Regarding the presence of the surface foundation, it should be mentioned that as expected due to the shallowness of the tunnel, the positive effect of the presence of the surface foundation was witnessed in the acceleration 0.1 g, 0.2 g, 0.45 g with the presence of the surface foundation. In the magnification of the acceleration of the upper surface of the tunnel, there is a decrease and in the acceleration of 0.96 g, the acceleration of the reduction of the acceleration of the upper surface of the tunnel also occurs.Finally, despite the high modulus of elasticity of steel compared to polyethylene, we see the expected performance and favorable agreement of surface acceleration magnification data with previous research data.
