At present, most studies believe that when the chloride ion concentration on the reinforcement surface reaches 0.05% of the concrete weight, the shield segment immediately loses its bearing capacity and reaches the end of its life. However, at this time, the structural bearing capacity does not reach the limited design state, resulting in the service life evaluation results of most lining segments being too conservative, and most studies cannot comprehensively consider the impact of shield segment monitoring data on its life evaluation. This paper presents a Bayesian dynamic evaluation method for the service life of lining segments under the condition of chloride ion erosion. This method considers the uncertainty of protective layer thickness, concrete compressive strength, and reinforcement tensile strength, realizes the whole process description of the reduction of segment bearing capacity caused by chloride ion erosion under time-varying action, and can dynamically update the service life of lining segments by using the existing monitoring data. The proposed method is applied to a tunnel project in the United States. The results show that the service life of the lining segment is only 37 years when only the chloride ion concentration is considered as the endpoint of life; however, the bearing capacity of segments under chloride ion erosion will not be suddenly small, so it is necessary to comprehensively consider the ultimate bearing capacity of segments. Both theoretical calculation and simulation calculation shows that segments will reach the end of life due to insufficient bearing capacity in the 80th year, while the structural bearing capacity has been reduced by 51.5% in the 100th year; Then, the existing observation data are used to dynamically update the theoretical data through Bayes formula. The results show that in the 75th year, the bearing capacity of the segment is reduced in advance and the service life of the segment is reduced by 6%. In practice, the protection needs to be strengthened in advance. The calculation process and results in this paper can provide a theoretical basis for the preventive maintenance of the segment lining of the tunnel.

Bayesian Dynamic Evaluation of Service Life of Lining Segments under Chloride Ion Erosion