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实际工程中,盾构隧道纵向弯矩和轴力可能同时存在,若按传统的纯弯等效抗弯刚度计算可能会带来较大误差。考虑轴力和弯矩共同作用对纵向弯曲变形的影响,提出5种弯曲模式,在经典的志波模型的基础上,建立盾构隧道纵向等效抗弯刚度计算模型,基于该模型开发了计算程序,以成都地铁3号线盾构隧道为实例,对其纵向等效抗弯刚度和管环张开量随轴力和弯矩的发展规律进行分析,并讨论弯曲模式的实用判别方法,求出变形过程的临界弯矩,最后给出纵向弯曲变形为线性和非线性的内力条件。研究发现:盾构隧道纵向变形随弯矩的发展过程可按轴力分为4类,各过程下管环张开量和等效抗弯刚度随弯矩的发展规律十分不同;轴力对等效抗弯刚度有显著影响,一般呈现压弯>>纯弯>拉弯的规律。研究成果可应用于盾构隧道结构纵向力学分析、抗弯刚度分析等方面。
In practical engineering, the longitudinal and axial loads of shield tunnel may exist at the same time. If calculated according to the traditional pure bending equivalent bending stiffness, it may bring greater error. Considering the influence of axial force and bending moment on the longitudinal bending deformation, five bending modes are proposed. Based on the classical Shibo wave model, a longitudinal equivalent bending stiffness calculation model of the shield tunnel is established. Based on the model, a calculation program Taking Chengdu Metro Line 3 shield tunnel as an example, the development law of longitudinal equivalent bending rigidity and tube ring opening with axial force and bending moment is analyzed, and the practical judgment method of bending mode is discussed, and the deformation process Of the critical moment, and finally gives the longitudinal bending deformation of linear and nonlinear internal force conditions. The results show that the longitudinal deformation of shield tunnel can be divided into four types according to the axial force during the development of the bending moment. The development of tubular ring opening and equivalent bending stiffness with bending moment are very different under each process. Bending stiffness has a significant impact, the general pressure bending >> Pure Bending> Bending Law. The research results can be applied to longitudinal mechanics analysis of shield tunnel structure and analysis of flexural rigidity.