类矩形隧道具有空间利用率高、双线一次成型等优点，但其受力性能不同于传统圆形隧道。盾尾是盾构壳体最薄弱的部分，有必要对类矩形盾尾的受力性能进行研究。本文以宁波轨道交通4号线工程为背景，建立类矩形盾尾的数值模型，分析、研究理想结构模型与考虑几何初始缺陷模型在多种工况下的受力性能，最后使用参数化方法，研究壳体厚度和覆土厚度对应力和变形分布的影响。结果表明： 盾尾设计具有足够的强度和刚度储备； 几何初始缺陷对盾尾变形的影响较大； 推进工况的摩擦力对应力和变形的影响很小，变向荷载主要增大了向外变形。

The quasirectangular tunnel has many advantages such as high utilization of space and onetime shaping of doubleline. The mechanical properties of such tunnels are different from that of traditional ones. The shield tail is the weakest part of the shield, hence it is necessary to study its mechanical properties. A numerical simulation model of quasirectangular shield tail used in Ningbo Rail Transit Line 4 is established; and then the mechanical properties of the ideal structure model and model considering initial geometric defect under different working conditions are analyzed; finally, the influences of shell thickness and soil thickness on deformation distribution of the shield tail are studied by parameterization method. The conclusions are drawn as follows: (1) The design of shield tail meets the strength and rigidity requirements of construction. (2) The initial geometric defects greatly affect the deformation of shield tail. (3) The thrust friction affects the stress and deformation little; and the steering load mainly increases the outward deformation. 