This paper presents an efficient two‐and‐a‐half dimensional (2.5D) numerical approach for analysing the long‐term settlement of a tunnel‐soft soil system under cyclic train loading. Soil deformations from train loads are divided into shear deformation under undrained conditions and volumetric deformation from excess pore water pressure (EPWP) dissipation. A 2.5D numerical model was employed to provide the dynamic stress state owing to the moving train load and the soil static stress state by the gravity effect for the determination of their accumulations. Then, an incremental computation approach combined with the initial strain approach in the framework of the 2.5D model was developed to compute the long‐term deformation of the tunnel‐soft soil system, considering the influence of the soil hardening due to EPWP dissipation. This approach helps to determine the distribution of the progressive settlement, transverse and longitudinal deformations in the tunnel‐soil system, overcoming traditional limitations. A comparison of settlements computed using this approach with measured settlements of a shield tunnel in soft soil shows good agreement, indicating the effectiveness of the proposed approach in analysing train‐induced progressive deformation of the tunnel‐soil system.

中文翻译：

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2.5D 数值公式，用于分析软土地区循环列车载荷引起的隧道土系长期沉降


本文提出了一种高效的二维半 （2.5D） 数值方法，用于分析隧道软土系统在循环列车载荷下的长期沉降。列车载荷引起的土体变形分为不排水条件下的剪切变形和超孔隙水压力 （EPWP） 耗散引起的体积变形。采用 2.5D 数值模型提供移动列车载荷引起的动应力状态和重力效应引起的土体静应力状态，以确定其积累。然后，在 2.5D 模型框架下开发了一种增量计算方法与初始应变方法相结合，以计算隧道软土地系的长期变形，同时考虑 EPWP 耗散引起的土硬化的影响。这种方法有助于确定隧道-土壤系统中渐进沉降、横向和纵向变形的分布，克服了传统的限制。使用这种方法计算的沉降与软土中盾构隧道的测量沉降的比较显示出良好的一致性，表明所提出的方法在分析火车诱导的隧道-土壤系统进行性变形方面的有效性。