This study investigates the vibration characteristics of a lossy tunnel invert and the propagation law of initial cracks under the dynamic load of a train, based on field tests conducted in the Fuchuan Tunnel of the Lanzhou–Urumqi High-Speed Railway. Dynamic resistance strain gauges were embedded in the invert structure and the propagation law of initial cracks under dynamic loads was studied using low cycle fatigue analysis. The results demonstrate that the attenuation of dynamic strain and dynamic stress in the shallow region of the tunnel invert was rapid and gradually slowed with an increase in depth. Furthermore, most of the dynamic stress was borne by the invert structure. Thus, the invert and its filling are the primary carriers of the dynamic load of the train. The initial crack below the track exhibits swivel propagation under the dynamic load of the train and extends until it penetrates the surface of the invert forming interconnected cracks. Consequently, the concrete in the crack loses its bearing capacity. Under the static load of the surrounding rock, the initial crack extends downwards, toward the centre of the invert. The initial crack at the centre of the invert also exhibits swivel propagation under the dynamic load of the train. Under the static load of the surrounding rock, the initial crack extends vertically downwards until it penetrates the central ditch. These results are extremely significant for the optimisation of tunnel invert design, to ensure the safety of train operations.

本文基于兰州—乌鲁木齐高铁富川隧道的现场试验，研究了有损隧道倒车的振动特性和列车动载荷下初始裂纹的扩展规律。将动态电阻应变仪嵌入倒置结构中，并通过低周疲劳分析研究了动载荷下初始裂纹的扩展规律。结果表明，随着深度的增加，隧道内底浅水区动应变和动应力的衰减迅速而逐渐减缓。此外，大多数动态应力由倒置结构承担。因此，逆变器及其填充是列车动载荷的主要载体。轨道下方的初始裂纹在列车的动载荷下表现出旋转传播，并一直延伸到穿透倒置表面，形成相互连接的裂纹。因此，裂缝中的混凝土失去了承载力。在围岩的静载荷作用下，初始裂缝向下延伸，朝向反演的中心。在列车的动载荷下，倒置中心处的初始裂纹也表现出旋转传播。在围岩的静载荷作用下，初始裂缝垂直向下延伸，直到它穿透中心沟。这些结果对于优化隧道反演设计，确保列车运行安全非常重要。因此，裂缝中的混凝土失去了承载力。在围岩的静载荷作用下，初始裂缝向下延伸，朝向反演的中心。在列车的动载荷下，倒置中心处的初始裂纹也表现出旋转传播。在围岩的静载荷作用下，初始裂缝垂直向下延伸，直到它穿透中心沟。这些结果对于优化隧道反演设计，确保列车运行安全非常重要。因此，裂缝中的混凝土失去了承载力。在围岩的静载荷作用下，初始裂缝向下延伸，朝向反演的中心。在列车的动载荷下，倒置中心处的初始裂纹也表现出旋转传播。在围岩的静载荷作用下，初始裂缝垂直向下延伸，直到它穿透中心沟。这些结果对于优化隧道反演设计，确保列车运行安全非常重要。在围岩的静载荷作用下，初始裂缝垂直向下延伸，直到它穿透中心沟。这些结果对于优化隧道反演设计，确保列车运行安全非常重要。在围岩的静载荷作用下，初始裂缝垂直向下延伸，直到它穿透中心沟。这些结果对于优化隧道反演设计，确保列车运行安全非常重要。