Analysis of Stress Characteristics of Specially Lined Segment of Superlarge-diameter Shield Main Tunnel during Mechanically Excavating Cross Passage
In this paper,the 6#cross passage of Haizhu Bay Tunnel,the first mechanically built cross passage of a superlarge-diameter shield main tunnel in China,is used as the example.First,the suitability of different types of specially lined segments in construction of mechanically built cross passage of a superlarge-diameter shield main tunnel is analyzed.Then the dynamic explicit finite element method is used to create a fine model that takes into ac-count cutterhead cutting and material damage failure,so as to investigate the stress characteristics of inlaid steel plate specially lined segment during construction of mechanically built cross passage.As the results indicate:In the mechanical construction process,the superlarge-diameter main tunnel experiences elliptical deformation.After cut-ting of the opening,both sides of the opening exhibit noticeable compressive stress concentration.Under the effect of the advancing cutterhead,major deformation increment and inter-ring dislocation are concentrated at the two sides of the opening.When inlaid steel plate specially lined segment is installed,the stress concentration of the structure at the sides of the hole in the cutting process is obviously abated,the deformation at the opening side is decreased by 0.5～1.5 mm,and the structure is made safer.Before construction,the inlaid steel plate of the special lining is welded into the whole structure,to enhance the integrity of the segments and to keep the inter-ring dislocation deformation of main tunnel at a low value.
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