| The shield tunnelling method is more and more widely used in recent years, and it has played an important role in the construction of river-crossing shield tunnels. With the construction of more and more river-crossing large shield tunnels, the study on structural mechancial behavior of the segments of large shield tunnels is more important. Based on the Wuhan river-crossing shield tunnel, this paper uses FEM and similar model test as the research means to systematically study the mechancial behavior and influencing rules of the structure of the large shield tunnel segment.(1) Adopting finite element numerical simulation analysis based on 'beam-spring' model, simplifying peripheral soil action as pulling and compressing and shearing spring action, entitling the segment to be beam element, and simplifying the joint to be rotating spring. By calculating and summarizing the deformations, moments, axial forces in the segment ring, studying the mechanics behavior of the segment ring in the case of different division methods, selecting the best division methods.(2) Taking geometric similarity ratio 1:20 and bulk density similarity ratio 1:1 as basic similarity ratio and carriing out indoor model test, realizing complete similarity in elastic range for controlled physical mechanical parameters. According to test results, studying the deformations, moments, axial forces of the segment ring which affected by water pressure,earth pressure and lateral pressure, then comparing the test results with the numerical simulation results, putting forward the method of selecting these paramaters when using different calculating modes.(3) According to test results and the numerical simulation results, studying the impact of complex geological condition on structure mechanical distributing of the segment ring, comparing it with normal condition, putting forward the structural mechanical behavior of the segment ring of large shield tunnel under complex geological condition.
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