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Nonlinear longitudinal equivalent bending stiffness of shield tunnel under the combined effect of axial force and bending moment |
GENG Ping,CHEN Pingliang,ZHANG Jing,HE Chuan,YAN Qixiang |
(MOE Key Laboratory of Transportation Tunnel Engineering,Southwest Jiaotong University,Chengdu,Sichuan 610031,China) |
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Abstract In practice,the bending moment and axial forces in the longitudinal direction of shield tunnel may exist simultaneously. The traditional method evaluating the equivalent bending stiffness under the conditions of pure bending may bring errors. In this paper,5 kinds of bending modes have been proposed to consider the combined effect of axial force and bending moment on longitudinal bending deformation. Furthermore,a model calculating the longitudinal equivalent bending stiffness of shield tunnel was established based on the classical SHIBA model. A computer program was written for the implementation of the model. The shield tunnel of Metro Line 3 in Chengdu as was analyzed. The practical method of determining the bending modes was discussed, the critical bending moment in deformation process,and the internal force condition of linear or nonlinear bending deformation were given. The results show that the process of longitudinal deformation of shield tunnel with bending moment can be divided into four categories according to the axial forces. The development of the equivalent bending stiffness and the opening of segment ring are very different. The axial forces has a significant effect on the equivalent bending stiffness,generally,the compression bending >> pure bending>stretch bending.
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[1] |
林永国,廖少明,刘国彬. 地铁隧道纵向变形影响因素的探讨[J]. 地下空间,2000,20(4):264-267.(LIN Yongguo,LIAO Shaoming,LIU Guobin. A discussion of the factors effecting on longitudinal deformation of subway tunnel[J]. Underground Space,2000,20(4):264-267.(in Chinese))
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