Design and calculation method of zero bending moment shield tunnel cross section

Abstract

The invention discloses a design and calculation method of a zero bending moment shield tunnel cross section. In the method, overall buried depth conditions, surrounding water and soil mechanical properties, underground water level conditions and the like of the top of a shield tunnel are analyzed according to formation conditions of the shield tunnel, the designed water and soil pressure mode of the shield tunnel is determined after comprehensive analysis, in this way, the rational axis and key parameters of shield tunnel cross section are designed, the cross section of the shield tunnel is of an egg-shaped structure which is small in the top and big in bottom, and the cross section theoretical bending moment of the shield tunnel cross section is zero under the effect of the designed water and soil pressure. The design and calculation method of the zero bending moment shield tunnel cross section has the advantages that the design and calculation method is simple and easy to operate, compared with a traditional shield tunnel, on the condition that the project cost is not basically increased, the bending moment of the designed zero bending moment shield tunnel is reduced to the greatest extent, therefore the cross section deformation of the shield tunnel and the expansion deformation of a pipe sheet longitudinal joint connector are avoided, breakage and water seepage of the pipe sheet longitudinal joint connector are prevented, and the using quantity of steel bars in a pipe sheet is reduced.

Description

technical field [0001] The invention belongs to the technical field of underground space engineering, and in particular relates to a design calculation method for the cross-section of a zero-moment shield tunnel. Background technique [0002] Such as figure 1 As shown, the cross-section of existing shield tunnels generally adopts a circular structure. In order to make reasonable use of the cross-sectional space or improve construction efficiency, there are also shield tunnels with other cross-sectional forms, such as transverse oval, rectangular, and quasi-rectangular (Ningbo Subway Line 3 adopts), semicircle, horseshoe, double circle, triple circle, etc. As an underground structure, the main load of the shield tunnel is earth pressure. Usually, the vertical earth pressure on the tunnel is greater than the horizontal earth pressure, which leads to the transverse elliptical deformation of the shield tunnel. As stipulated in the subway design code, the maximum ellipticity de...

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Problems solved by technology

However, in practice, it is impossible to set all segment longitudinal seam joints at the position where the bending moment is 0, and for the operability of construction, there must be a certain number of segments in the tunnel ring direction

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