TN814 : Numerical assessment of influence of soil parameters on the seismic response of concrete segmental tunnel lining
Thesis > Central Library of Shahrood University > Mining, Petroleum & Geophysics Engineering > MSc > 2017
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Abstarct: Nowadays, considering the increasing trend of world population, as well as the need to move and transport people in urban environments, application of underground structures is increasing day by day. In order to transport people under the ground, underground trains (subways) are utilized which move through tunnels excavated by machined methods. Also in Iran, these tunnels have been used in metropolises such as Tehran, Mashhad, Tabriz, Shiraz, etc. In these tunnels, precast concrete segments are used as linings.
One of the factors that causes the axial and shear forces as well as the bending moment in the tunnel concrete lining is earthquake. Despite the fact that the tunnels have high security against the structures constructed on the ground, the recent damages caused by the earthquake to some of these tunnels highlighted the need for considering a dynamic load when designing underground structures.
Due to the fact that Iran is considered as one of the seismic countries in the world, study of the stability of these tunnels against earthquake loads is of particular importance. Various factors affect the amount of damage caused by earthquake, including the frequency content of earthquake waves, the parameters of tunnel environment and protective lining of tunnel, as well as its dimensions.
The purpose of this study was to investigate the parameters related to the tunnel environment by numerical methods, and compare these results with analytical methods. For this purpose, the effect of environmental parameters of the tunnel on the performance and response of concrete segments of tunnel lining under seismic loading has been investigated. In this regard, numerical analysis were carried out in different soil environments by finite difference method and using FLAC3D software. The FLAC3D software is capable of modeling the behavior of structures constructed in soil, stone and other materials that may show non-linear behavior.
In order to investigate the research topic, the dynamic response of concrete segments baxsed on axial force, shear force and bending momentum has been studied and a comparison between the results of numerical modeling with analytical methods is presented which has been developed for continuous lining.
Generally, the results of the research show that with increase in deformation modulus and the internal friction angle of soil, the amount of maximum bending moment increases, the maximum axial force is first reduced and then increased and shear force increases. By increasing the thickness of the lining, the bending moment of the tunnel is significantly increased, but no change happens in the axial force and maximum shear force. Also, with the increase in the number of concrete segments of the lining, the maximum bending moment, axial force and maximum shear force are reduced.
Keywords:
#Dynamic Analysis #Numerical Methods #Tunnel #Precast Concrete Segments #Earthquake Link
Keeping place: Central Library of Shahrood University
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Keeping place: Central Library of Shahrood University
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