The modified routine modelling (MRM) and the beam spring modelling (BSM) are two of the classical design methods for circular shield tunnels, but a comparison between their applications in special-section shield tunnels (SSSTs) has not yet been conducted. In this study, these two methods are investigated and compared specifically for the case of quasi-rectangular shield tunnels (QRSTs). While the MRM gives acceptable results for axial force values, some critical bending moments in joint sections and segment sections can be overestimated or underestimated, not giving accurate values for design. It is demonstrated that the MRM cannot precisely predict the degree of bending moment transfer and convergence deformations of the studied SSST, and should only be used in preliminary design. On the other hand, deeper insights into the mechanical behaviour of the QRST lining structure can be gained through the analysis of the BSM. The staggered assembly pattern results in a bending moment transfer between rings and the relatively stiff area sustains the transferred moment from its neighbouring less stiff areas. For most of the longitudinal joints, 20% to 40% of bending moment is redistributed to its neighbouring segments. The transfer increases the non-symmetric distribution of bending moments in the two halves of a QRST lining ring. This characteristic does not exist in a traditional circular shield tunnel but needs due attention to the types of shield tunnels with two compartments in one tube. Finally, the influences of different parameters related to the assumed pressures and soil reactions are discussed.

中文翻译：

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特殊断面盾构隧道梁弹簧法与修正常规法对比研究——以准矩形隧道为例

改进的常规建模（MRM）和梁弹簧建模（BSM）是圆形盾构隧道的两种经典设计方法，但尚未对其在特殊断面盾构隧道（SSST）中的应用进行比较。在这项研究中，这两种方法专门针对准矩形盾构隧道（QRSTs）的情况进行了研究和比较。虽然 MRM 给出了可接受的轴向力值结果，但接头部分和节段部分的一些临界弯矩可能被高估或低估，无法为设计提供准确的值。结果表明，MRM 不能准确预测所研究的 SSST 的弯矩传递和收敛变形程度，只能用于初步设计。另一方面，通过对 BSM 的分析，可以更深入地了解 QRST 衬里结构的力学行为。交错的组装模式导致环之间的弯矩传递，并且相对刚性的区域承受来自其相邻刚性较小的区域的传递的力矩。对于大多数纵向节点，20% 到 40% 的弯矩被重新分配到其相邻节段。这种传递增加了 QRST 衬环两半中弯矩的非对称分布。这一特点在传统的圆形盾构隧道中不存在，但需要注意一管两室的盾构隧道类型。最后，讨论了与假设压力和土壤反应相关的不同参数的影响。