Structural fire investigation and analysis on rectangular shield tunnel assembled by composite segments

Abstract

Rectangular shield tunnels have been extensively used in roads, railways, stations, etc. In this paper, the structural responses of rectangular shield tunnel assembled by composite segments under fire were investigated. The elaborate numerical model was established based on the real rectangular shield tunnel and relevant assumptions were proposed based on matters of fact to enhance the computational efficiency of the model. In both ambient and elevated temperature conditions, the reliability of the finite element model is validated by previous experimental results. Afterward, parametric studies were also performed by a series of numerical simulations by varying parameters such as fire curves, loading conditions, and material types. This involved calculating the temperature distribution and internal forces in steel plates and concrete, as well as examining lining deformation, joint opening, and vulnerability. According to the results, during the cooling stage of RABT curve, the joint opening can be reduced by more than 30% on average and up to 50%. Load conditions have a significant effect on the mechanical response of the tunnel structure, especially the deformation. In addition, under the effect of RWS fire curve, the structure of lower-degree concrete is unstable. The results contribute to the fire-resistant design of rectangular shield tunnels assembled with composite segments.