Analysis and calculation method of effective bending rigidity ratio in modified routine method

As a practical calculation method for the lining structure of shield tunnels, the modified routine method has been widely applied during its design. The key parameter, the effective bending rigidity ratio η, is essential for the calculated results. The numerical models for segmental rings with and without joints are established using the load structure method. Based on the results of the FEM analysis, the influences of number, distribution and bending stiffness of joints and soil resistance coefficient on the effective bending rigidity ratio are examined. The study indicates that the effective bending rigidity ratio increases when the number of joints decreases or the bending stiffness of joints and the soil resistance coefficient increase. In addition, the distribution of joints has appreciable impact on the effective bending rigidity ratio. A method for evaluating the effective bending rigidity ratio of shield tunnel structures is proposed. The effects of number, distribution and bending stiffness of joints and soil resistance coefficient are considered. Through comparisons, the proposed method is proved to be practical and accurate.