TN672 : Study of sequential excavation effect for large span urban tunnels in soft ground on the settlement Case study: Tehran Chitgar tunnel
Thesis > Central Library of Shahrood University > Mining, Petroleum & Geophysics Engineering > MSc > 2016
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Abstarct: Having human improved and developed his abilities in all of the fields and having population growth per day, the need to faster transport systems containing more capacities is sensed strongly. Sure one of the best, purest, most quick, and containing most capacity of this systems, are underground transport webs. This webs contain Metro, underground highways, and underground pavements. Nowadays tunneling in citizen areas is an important matter because of less space and keeping the environment healthy manner. Tehran is not an exception. For this reason different kinds of tunnels and undergrounds have been operated there especially recent years. Hakim tunnel for example is one of the both side traffic highways which is used to transport traffic bars between Tehran and Karaj passing through Chitger woods. The mechanisms of operating this tunnel, is a masterwork for Tehran, keeping Chitger woods as breathing lungs of this city at a regarding healthy environment point of view. Operating Hakim tunnel in a region which contains masses of soils and laxyers which are not hard enough, has risks such as surface subside. Investigating, measurement, and controlling of such matters, can reduce this risks in a high and sizable degree. Aiming this achievement, needs to different factors involved such as suitable digging excavation methods, proper sequences of digging the different parts of a tunnel, the appropriate distances between different digging projects excavation faces of two tunnels, and so on should be investigated and controlled. One of the most important one of this factors, is proper sequences of digging. Meaning that in digging a tunnel project having a great segment surface, and being done in several stages (NATM method), sequences of digging the several parts toward each other should be evaluated well.
In the present research, first we have designed and analyzed the conservation systems of this tunnel using Finite element analysis (FEA), PLAXIS 3D Tunnel numeral modeling software. Then the effect of sequential excavation of different parts of Hakim tunnel upon surface subside has been investigated. In the next stage the distances between different excavation faces towards each other in one tunnel, and afterwards the distances of excavation faces between two tunnels are evaluated. According to obtained results, using A type excavation sequences will result in least surface subside which is 29 mm theorically. Also the distances between the enteral excavation faces of a tunnel should be fixed and more than 1D (D is the tunnel diameter) along all the rout of tunnel. Furthermore the distances between faces of the two tunnels should be regarded at least 3D until the two excavation faces don’t have sensible impact on each other.
Keywords:
#tunneling #NATM #PLAXIS 3D Tunnel software #surface subsidence #sequential excavation #distances Link
Keeping place: Central Library of Shahrood University
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Keeping place: Central Library of Shahrood University
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