The fabricated lining is widely used in the underground rail transit, water conveyance system and river-crossing tunnel. It is generally composed of the precast concrete segments, joints, bolts and reinforcements. Compression and separation often coexist in a single joint, which brings great challenges to the modeling and calculation of the fabricated lining. In this paper, an independent cover isogeometric Reissner-Mindlin shell model (denoted as the ICI-R shell model) is proposed for the simulation of the fabricated lining. In the ICI-R shell model, each segment is regarded as an independent cover, whose geometry is described with the nonuniform rational B-splines (NURBS) surface, and an isogeometric displacement function is defined based on the Reissner-Mindlin shell deformation theory. The adjacent segments are connected with the fictitious thin layers, of which the normal and tangential deformations and stresses can be correctly calculated. Within this framework, the difficulties in the continuity-discontinuity coupling analysis occurring when using the existing shell models are well solved, and the fabricated lining can be simulated expediently. The ICI-R shell model has the advantages of clear physical meaning, concise formulas and convenient implementation. Benefiting from the strong capability of representing geometries of NURBS and the simplicity of the formulation of the ICI-R shell model, the parameterized modeling and automatic calculation of the fabricated lining can be easily achieved for simplifying the analysis process and reducing user cost for geotechnical engineers. The successful application in the benchmark tests and engineering example shows the versatility, efficiency and robustness of the ICI-R shell model.

中文翻译：

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用于模拟装配式衬砌的独立覆盖等几何 Reissner-Mindlin 壳模型

装配式衬砌广泛用于地下轨道交通、输水系统和过江隧道。它通常由预制混凝土管片、接头、螺栓和钢筋组成。压缩和分离往往同时存在于一个接头中，这给装配式衬砌的建模和计算带来了巨大的挑战。在本文中，提出了一个独立的覆盖等几何 Reissner-Mindlin 壳模型（表示为 ICI-R 壳模型），用于模拟装配式衬砌。在 ICI-R 壳模型中，每段被视为一个独立的覆盖层，其几何形状用非均匀有理 B 样条 (NURBS) 曲面描述，并基于 Reissner-Mindlin 壳变形理论定义等几何位移函数。相邻段与虚构的薄层相连，可以正确计算法向和切向变形和应力。在此框架内，很好地解决了使用现有壳模型进行连续-不连续耦合分析的困难，并且可以方便地模拟装配式衬砌。ICI-R壳模型具有物理意义明确、公式简洁、实现方便等优点。受益于NURBS强大的几何表达能力和ICI-R壳模型公式的简单性，可以轻松实现装配式衬砌的参数化建模和自动计算，为岩土工程师简化分析过程，降低用户成本.