Research On Segment Structure Theory Of Shield Tunnel And Its Engineering Application

The fast growing world economy has greatly promoted the development ofurbanization after entering the twenty-first century,with the rapid development and thesaturation of the cities’ surface space utilization, the mankind is gradually paying moreand more attention to the vast underground space. Not only in China but also all overthe world, Shield tunnel has become one of the most important building method in thelarge number of subway constructions. Benefit from the shield tunnel’s own advantagesand the promotion of the large-scale constructions in urban infrastructure andunderground space, Not only the shield tunnel construction technology but also itstheory has made a great progress. However,due to the complexity of the undergroundstructures and geotechnical engineering characteristics, the calculation model of shieldtunnel is far from perfect. So the constantly theoretical research of shield tunnelcalculation model which can best reflect the actual engineering situation is in need. Inthis paper, theoretical calculation of shield tunnel structure has been studied, the majorpoints of this thesis are as follows:Firstly, this paper has reviewed the history of the shield tunnel,then, a summaryabout the worldwide shield tunnel calculation model and related theory has beenpresented,besides, in this paper, some common models, such as the routine method (freedeformation method), modified routine method, the elastic multi-hinge model, thetwo-ring of beam-spring model and beam-joint model are described in detail.Secondly, The different load calculation methods and their application conditionsof the shield tunnel are summarized in this paper,the load calculation methods of theshield tunnel are discussed. The simplified calculation of the soil pressure, the feedbackanalysis method and the method that considers the interaction between lining andformation are introduced, besides,the simplified calculation of the vertical soilpressure,the horizontal soil pressure, the ground resistance pressure and other basicsegment issues are studied in detail.Thirdly, Based on the Nanchang Metro Line one project, this paper studies theinternal force calculation law of shield tunnel under the influence of the effectivebending stiffness and the soil resistance coefficient by using the uniform rigidity ringmodel. Taking into account the different model assumptions and calculationcharacteristics between the uniform rigidity ring model, the elastic multi-hinge modeland the two-ring of beam-spring model, some related research and analysis is carried out, from which some valuable conclusions are gained.Finally, In this paper,an analytical solution of shield tunnel calculation model thatconsiders joint stiffness and the changing distribution of soil resistance is derived and iscompared with the uniform rigidity ring model and the numerical simulation. Thecomparative analysis shows that: The internal force of shield tunnel that calculated bothby the deriving analytical solution method and the uniform rigidity ring model methodalmost have the some trends;besides, the internal force of shield tunnel that calculatedboth by the deriving analytical solution method and the numerical simulation methodalmost have the same trend too.The results that calculated by the three different methodsare consistent to each other, especially when the tunnel’s diameter increases. Becausethe deriving analytical solution’s basing on the assumption that loosens the restriction ofthe soil resistance, it has some applicability and universality.Reasonable calculation model of shield tunnel is of great significance to improvingdesign level,reducing cost,controlling safety and so on.