Research On Comprehensive Evaluation Method Of Railway Tunnel Condition And Maintenance Cycle Strategy

During tunnel usage,structural deterioration is unavoidable due to inherent defects and external factors,leading to various damages such as water leakage,cracking,and spalling.These defects worsen over time,posing significant risks to tunnel safety and normal operation.Accurately assessing the actual condition of the tunnel is crucial to ensure its safe and effective use.However,different departments have distinct focuses on tunnel condition assessment,resulting in a lack of standardized evaluation criteria.This issue leads to redundant work and increased overall costs.Therefore,it is essential to address key challenges,including concise and reliable tunnel condition assessment,establishment of applicable grading standards,and development of a scientific inspection system.These aspects are crucial for achieving a comprehensive lifecycle evaluation of tunnels while meeting the evaluation needs of various stakeholders.To address these challenges,this study first investigates the conversion rate of typical defects and damages in tunnels,aiming to understand the impact of abnormal conditions on tunnel functionality and safety.Specific defects or damages are selected for in-depth investigation and statistical analysis to comprehend their developmental characteristics.Subsequently,the study analyzes the requirements for assessing the lining condition at different stages of tunnel construction,examines the mechanisms of various influencing factors on the lining condition,and establishes a tunnel lifecycle condition evolution model.Moreover,an index system for lining condition assessment is analyzed and formulated.Based on numerical simulation or existing research statistics,a grading standard for lining deterioration is established.The study also clarifies the influencing factors and determination methods for each evaluation index.Finally,a variable fuzzy evaluation method for lining condition is developed,and a reliability analysis model considering the lining condition is constructed.Additionally,a maintenance cycle calculation model is established based on the evolution pattern of tunnel condition under different maintenance modes.The main research outcomes are as follows:(1)The study analyzes the impact of different factors on the lining condition and establishes a nonlinear stochastic time-varying system model to describe the lining deterioration process.A time-based model is employed,and a Poisson noise is introduced to capture the randomness and fuzziness of the lining deterioration.(2)An evaluation index system is established based on the Analytic Hierarchy Process,consisting of five criteria-level indicators and fourteen scheme-level indicators.The sensitivity and correlation of different indicators to tunnel durability,applicability,and safety are analyzed.Through quantitative and qualitative principles,a five-level grading standard("healthy," "basically healthy," "moderate," "severe," and "critical")is determined.The importance of different level indicators is compared and analyzed.The fuzzy Analytic Hierarchy Process is utilized to determine the weight relationships between the evaluation indicators,employing the product-scale method to determine the weights between different evaluation indicators.(3)The variable fuzzy theory is employed to perform targeted evaluations of the lining at different stages.By altering the model parameters,level characteristic values of different parameter combinations can be calculated,and their stability is analyzed to determine the final condition level of the lining.A reverse description model of the lining system’s reliability is established,enabling determination of the relationship between the lining condition level and tunnel reliability.The reliability of the lining can be calculated to understand its condition level,and conversely,the evaluation of the tunnel’s condition level allows for determining the tunnel’s reliability.By equating the degree of deterioration to the equivalent replacement of lost service time,a state evolution model is established for tunnels in different maintenance states.The failure probability of the tunnel is determined using a Weibull model,and a maintenance cycle model is developed based on maintenance costs.