During the parallel operation of excavation and concrete lining construction in the diversion tunnel, the quality of construction was significantly affected due to the severe damage to the floor concrete caused by heavy truck crush. In response to the challenging problem of floor concrete protection caused by heavy truck crush during the "excavation-lining" parallel operation in the diversion tunnel, a numerical calculation model for floor protection was established using ABAQUS. Adopting the floor protection measure of overlaying "tunnel excavation debris-concrete" composite protection layer, a numerical simulation study on the protection of tunnel floor concrete was conducted. The influence patterns of the material characteristics of the protection layer and the bias distance of the heavy truck on the stress and deformation of the floor concrete were analyzed, and the effectiveness of protection under different working conditions was evaluated. The study results indicated that the floor protection measures could effectively improve the protection of the floor concrete. As the concrete grade of the protection layer increased, the stress and deformation of the floor concrete decreased, with the reduction rate reaching up to 17.5% and 12.4% respectively. Furthermore, as the bias distance of the heavy truck increased, the maximum deformation of the floor concrete increased, and the range of deformation expanded significantly. Moreover, stress growth was extremely pronounced at the edges, with a maximum growth rate of up to 222.6%. The research results can provide theoretical and technical guidance for the protection of the floor concrete against crush damage in the diversion tunnel.