Time-Dependent Reliability Analysis and Maintenance Strategy for Fully Enclosed High-Speed Railway Noise Barriers

To assess the long-term fatigue safety of fully enclosed high-speed railway noise barriers and to optimize maintenance strategies, a time-dependent probabilistic reliability framework focusing on fatigue damage and bolt preload relaxation is developed. The stochastic nature of train velocity, load scaling factor, and daily traffic volume is explicitly considered. Using the 350 km/h two-train passing scenario as the reference case, the stress time history at the column base is extracted. The damage per train pass is computed via rain-flow counting and Miner’s rule, and the time-dependent reliability indices are obtained through parallel Monte Carlo simulations (104 samples, daily time steps over 50 years). The results show that the fatigue failure probability at 50 years is 0.11%, with a reliability index β ≈ 3.06 and a mean cumulative damage of 0.325; failures are concentrated in the 40–50-year period, and train velocity is identified as the most influential factor. Furthermore, 98.3% of the bolts require retightening within 50 years, with a median intervention time of 18.2 years—far earlier than the occurrence of fatigue failure. The joint system analysis reveals that the overall system failure is dominated by bolt relaxation; when the coupling effect is included, the fatigue failure probability increases to 0.18%. A phased maintenance strategy is accordingly proposed: monitor preload during years 0–15, perform comprehensive re-torquing during years 15–30, and intensify fatigue inspections during years 30–50. The proposed methodology provides a quantitative basis for life-cycle safety assessment and operational decision-making for fully enclosed high-speed railway noise barriers.