基于柔度法梁模型的盾构隧道衬砌结构纵向变形计算方法

COMPUTATION METHOD FOR LONGITUDINAL DEFORMATION OF SHEILD TUNNEL LINING STRUCTURE BASED ON FLEXIBILITY BEAM MODEL

由于纵向力及螺栓屈服等因素的影响,盾构隧道衬砌结构的纵向抗弯刚度沿隧道轴线分布并不均匀。针对该问题,引入隧道在附加沉降变形条件下的典型内力分布模式构造内力形函数,建立基于柔度法的盾构隧道衬砌结构纵向梁模型,并通过在轴向和环缝两个层次引入数值积分方法进行求解;基于该模型,得到了在柔性边界和刚性边界两种典型边界下沿隧道轴线的环缝变形分布,并讨论了数值积分策略对于计算结果的影响。研究结果表明:纵向力和螺栓屈服的影响在结构纵向变形计算中不可忽略,而考虑以上两点因素后,结构由于受局部集中变形的影响,位移模式将非常复杂,所提出的柔度法模型则能够避免传统刚度法模型在处理该问题上的局限性,从而用很小的计算代价获得较为精确的隧道结构纵向变形。

The longitudinal bending stiffness of a shield tunnel is not uniform along the tunnel because of the influence of a longitudinal force and the yielding of longitudinal bolts. Aiming to solve this issue, a typical inner force distribution mode under the uneven settlement of a shield tunnel was first introduced to build inner force shape functions. Then, a flexibility beam model was established with the aid of the numerical integration method in longitudinal and circumferential level. Based on this model, the distribution of circumferential joint deformation along the tunnel axis under flexible and rigid boundary conditions was derived. The influence of the integration strategy on the calculation accuracy was also investigated. The results show that： 1） the longitudinal axial force and yielding of bolts are two important factors in the calculation of structural longitudinal deformation, which should not be neglected, 2） the deformation pattern of the structure is very complicated as local concentrated deformation is considered. The proposed flexibility model could avoid the limitation of dealing with the complex deformation pattern in traditional stiffness models, and provide an accurate method to calculate the longitudinal deformation of a shield tunnel lining structure with little computational cost.