矩形管片隧道纵向等效抗弯刚度与抗弯性能研究

Longitudinal Equivalent Bending Stiffness and Bending Performance of Rectangular Segmented Tunnel

摘要:

基于等效连续化模型，推导了矩形管片隧道在任意压弯组合状态下的纵向等效抗弯刚度计算方法，并针对矩形管片隧道的特点，对4种不同中性轴位置的等效抗弯刚度计算方法分别进行了讨论。在此基础上，进一步分析了压弯比、宽厚比、螺栓个数以及截面形状等关键设计参数对抗弯刚度的影响，并给出了4种中性轴位置转变对应的临界压弯比。研究结果表明：隧道纵向抗弯刚度有效率随着压弯比、螺栓的个数以及环宽厚比的增大而增大，而随着截面宽厚比和宽高比的增大而减小。中性轴的位置不仅仅与截面的尺寸以及材料属性相关，还与压弯比的大小有关。临界压弯比随着截面宽厚比的增大而减小，且对截面形状变化表现敏感。上述结论对于矩形管片的优化选型及设计计算具有重要理论参考价值。

Abstract:

Based on the equivalent continuous model， this paper deduces the longitudinal equivalent bending stiffness of rectangular shield tunnels under the combination state of compression and bending. Considering the cross-sectional characteristics of rectangular shield tunnels， the closed-form solution of the equivalent bending stiffness under four neutral axis positions is discussed， based on which， a parametric analysis， using the new analytical solution， is conducted to investigate the effect of key parameters on the longitudinal bending stiffness， including the ratio of compression to bending， the number of bolts， the ratio of width to thickness and so on. The critical value of N-M ratio for different positions of the neutral axis is further obtained. The results show that the longitudinal bending stiffness efficiency increases with the increase of the compression-bending ratio， the number of bolts and the ring width-to-thickness ratio， but decreases with the increase of the sectional width-to-thickness ratio and aspect ratio. The position of the neutral axis is not only related to the size of the cross-section and material properties， but also to the compression-bending ratio. The critical value of N-M ratio decreases with the increase of sectional width-thickness ratio and is sensitive to the change of sectional shape. The conclusion has important theoretical reference for optimal selection and design calculation of rectangular segments.