| Carbonization erosion is the leading cause of the deterioration of the reinforced concrete structure.As for highway tunnels,it mainly has the characteristics of heavy traffic and slow air flow.And due to the semi-closed structure of the tunnel,there are large differences in temperature,humidity and carbon dioxide concentration between the inside and outside of the tunnel.At the present,when designing the durability of the carbonization of the lining structures,the ordinary atmospheric environmental parameters are often used to calculate the concrete carbonation depth,which has obvious shortcomings.In this paper,based on the operating environment of the highway tunnel,the method of theoretical calculation and numerical simulation is used to study the distribution of temperature,humidity and carbon dioxide concentration in the highway tunnel,as well as the environmental zonation of tunnel lining carbonation.First of all,according to the monitoring data,the distribution of temperature and humidity inside and outside the highway tunnel is analyzed,and the temperature and humidity zoning maps of different highway tunnel environments in China are established.Secondly,based on the diffusion theory of vehicle pollutants,the convection-diffusion equation of carbon dioxide in the highway tunnel is established,and a more suitable calculation method of carbon dioxide concentration in highway tunnel is given.Thirdly,the diffusion of carbon dioxide concentration in the tunnel is simulated by Fluent software,and the variation and distribution of carbon dioxide concentration under different tunnel length,traffic volume,and wind speed are analyzed.Through regression analysis,the calculation formula of maximum carbon dioxide concentration in the one-way tunnel with longitudinal ventilation is given.Finally,according to the distribution characteristics of the environmental parameters of the highway tunnel,the environmental zonation of the lining structure in China is established by the principle of equal degradation gradient.And the calculation process of the maximum carbonation depth of lining structure under different service years is given. |
