Abstract: In order to explore the fire behavior law of urban tunnel concrete walls under fire, the finite element software ABAQUS was used to establish a three- dimensional concrete wall numerical model, and the temperature field distribution of the structure was simulated by numerical simulation method. The effects of factors such as wall thickness, concrete cover thickness and axial compression ratio on wall deformation were analyzed. The results showed that the temperature of the heated surface of the concrete wall rises rapidly under fire, and a large temperature gradient will be formed inside due to the thermal inertia of the concrete. The deflection change of a concrete wall can be divided into three stages when one side is subjected to fire, and the main factor affecting the deflection change of wall is the deviation of section neutral axis caused by the rapid deterioration of material performance caused by the high temperature of fire. Factors such as the thickness of the reinforced concrete wall, the concrete cover thickness and the axial compression ratio all have certain influence on the fire behavior and fireresistance performance of the concrete wall. The wall deflectionwill increase with the increase of the fire duration.

Key words: concrete wall, tunnel fire, temperature distribution;fire behavior, influence factor, numerical simulation