| The shield tunneling method is more and more widely used in recent years, and ithas taken an important role in the construction of subway in large city. The study onthe stress of the segments (the segments of tunnel shield) is more important. The keyof the segment in tunnel shield design is selection of the design method. Along withthe cognition to the restriction of the formation to the segments increases, the segmentdesign with the characteristic of the interacting of formation and structure forms. Thefactors that reflect the stress of the segments include geological parameters andstructure parameters. Compared with the latter, the former has more uncertainty butless accuracy. There are four major segment designs recently, thus Routine Method(Free Deformation Method), Modified Routine Method, Spring Foundation-CirqueMethod and Beam-Spring Model Method, and they have strongpoint anddisadvantage. The key of this paper is ,base on this five major segment designs, tobuild a math model of Peripheral Spring Foundation -Straight Beam-Spring Hingein segment design ,by the comparison of data, analyzing the strongpoint anddisadvantage of this math model on the segment in tunnel shield design . The followis the main research route of this paper. Firstly, basing on the comparison of theoretical analyzing of the RoutineMethod (Free Deformation Method), Modified Routine Method and Beam-SpringModel Method respectively, and put forward the appropriate design math model ofPeripheral Spring Foundation -Straight Beam-Spring Hinge on the segment intunnel shield design. Secondly, Mechanics analyzing and simplifying the segment structure basingon the math model of Peripheral Spring Foundation -Straight Beam-Spring Hinge ,thus simplifying peripheral soil action as pulling and compressing and shearing springaction, entitling the segment to be straight beam element, and simplifying the jointto be Spring hinge, the relative turning action is only taken into account . FLACsoftware is adopted for numerical simulation of the selected segment structure.Thirdly, taking example on Beijing subway 4th routine tunnel shield (Beijingzoo ~ Baishi bridge) segments design, Comparing and analyzing the result datacoming from this two numerical models, the two models are Free DeformationMethod and Peripheral Spring Foundation - Straight Beam - Spring Hinge.Discussing and analyzing the difference on the results in moment value and shearingforce and force and distortion, and discussing the good and bad facet, wishing it canprovide useful data for segments design. |
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