Deformation control method for inverted arch in railway tunnels

Support and maintenance of tunnel excavations during operation are critical to ensure the safety and stability of tunnels. This study proposes a specialized support technology for a railroad tunnel in western China, characterized by substantial deformation and a limited inherent self-stabilizing capacity. The method involves the application of a foam concrete compressible layer at the inverted arch of the tunnel. The effectiveness of the foam concrete layer in mitigating the effect of the surrounding rock on the tunnel inverted arch structure is investigated by a combination of indoor tests and numerical simulations. The laboratory test results show that the train load has little effect on the compressive performance of the foamed concrete compressible layer, which indicates that the foamed concrete compressible layer can be applied in the tunnel invert. By analyzing the support effect of the established model, it is found that the foam concrete compressible layer can effectively absorb the deformation pressure generated by the surrounding rock and protect the secondary lining structure, when the compressible layer density is 500 kg/m³ and the thickness is set to 20 cm, the supporting effect is the best.