The Large Span Of Half-dark Arch Tunnel Construction Technology Research, And Mechanical Properties

At present, when constructing senior highway or municipal road in China , double-arched tunnel is often adopted in special geological and topographical area in order to get better technological and economical purpose.Because the span of double-arched tunnel is large, when terrain height difference is large on the cross-section and the axis of the tunnel is skew to topographic contours, in order to avoid excessive slope excavation on the one side and the less cover of the tunnel on the other side , the new type of half-embedded & half-uncovered double-arched tunnel is invented.As a special double-arched tunnel structure, it is researched less on its design, construction and other aspects, therefore it is necessary to analyze the construction mechanical characteristics of half-embedded & half-uncovered double-arched tunnel.This paper, based on the Jin'e tunnel as an example, by means of numerical simulation and measurements at the scene, thoroughly discussed its construction mechanical characteristics.In this thesis, the main content are followed:1 .Using Finite Difference Method ,the two construction methods(the uncovered tunnel is firstly excavated and the hidden hole is secondly excavated, the hidden hole is firstly excavated and the uncovered tunnel is secondly excavated) of half-embedded & half-uncovered double-arched tunnel is dynamic simulation through two-dimensional way.Through the stress, displacement under the different method are analyzed, in the final the two methods is the same.2.By adopting the three-dimensional numerical means, the rock stress, the displacement and the tunnel lining of the characteristics during the construction process on the spot are analyzed, at last the details,the key and important part of the construction steps are determined and the corresponding measures are put.3.Making use of the measurement method on the construction site , the change law of the surface sink ,the surrounding rock convergence ,the vault crown settlement and the internal force of the primary support and the secondary lining are tracking and discussed, the rules of those are summarize.4.The results of numerical analysis and the results of the measurement were comparatively analyzed.The result of analysis shows that they are basically same.The conclusions in this paper may provide some reference value to other similar projects.