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| STUDY OF THE PERMISSIBLE VALUE OF UPWARD FLOATING FOR SEGMENT IN SHIELD TUNNEL CONSTRUCTION |
| YE Junneng1，LIU Yuan2，3，4，CHEN Renpeng2，3，TANG Lujun2，3 |
| (1. Ningbo Urban Rail Transit Project Construction Headquarter，Ningbo，Zhejiang 315012，China；2. MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering，Zhejiang University，Hangzhou，Zhejiang 310058，China；3. Institute of Geotechnical Engineering，Zhejiang University，Hangzhou，Zhejiang 310058，China；4. Changjiang Survey，Planning， Design and Research Co.，Ltd.，Wuhan，Hubei 430010，China) |
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Abstract The excessive upward floating of segment in shield tunnel construction would cause the ring joints stretched，dislocated and segment damaged. At present，there are few researches on the permissible value of upward floating for segment in shield tunnel. By using finite element software ABAQUS，a 3D numerical model for the analysis of upward floating which could consider the impact of dislocation and stretched deformation of spring join was founded. The upward floating deformation at different segments and the deformation of spring joints were analyzed. Results show that upward floating of segment can be divided into three stages：the linearly developing stage，the arc-shaped developing stage and the deformation stabilized stage. The main deformation of joints is dislocation in the linearly developing stage and tensile in arc-shaped developing stage. A formula for the permissible value of upward floating for segment in shield tunnel which is affected by the permissible dislocation value and permissible tensile value of spring joint was obtained. The permissible value of segment upward floating of Ningbo and Shenzhen metro whose structure of segment are different were compared，and result shows that the structure of segment has great impact on the permissible value of upward floating.
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2014, Vol. 33 
