Study On Structural Health Monitoring And Safety Evaluation System Of Underwater Highway Tunnel

During the construction and operation of the tunnel structure,due to various factors,a series of disease problems occurred during the service phase.Especially for the underwater tunnel,due to the special nature of the environment,the structural deterioration of the tunnel is more serious.The emergence of these diseases not only affects the practical function of the tunnel,but also reduces the safety during the tunnel use process,which brings certain operational risks.In order to ensure the safety of the tunnel during the construction period and operation period,it is necessary to timely understand the health status of the tunnel structure and evaluate its safety in a timely manner.Therefore,it is necessary to carry out the research on the structural health monitoring and safety assessment system of the underwater highway tunnel,and to evaluate the safety status of the tunnel structure in real time.Based on the Lujiashi tunnel,this paper focuses on the research on the health monitoring and safety evaluation of the main structure of the underwater highway tunnel,and uses the research methods such as literature research,numerical simulation and theoretical analysis to obtain the following research results:1.Based on the Lujiashi underwater highway tunnel,various risk factors affecting the structural health of the tunnel were identified,and these factors were divided into three types: the environment of dangerous source,structural defects and load effect.Through the research and analysis of the causes of various risk factors and their influence on the tunnel structure,the corresponding monitoring indicators were selected,and the influencing factors of the tunnel structure health state were established,which laid a foundation for the study of tunnel structure safety evaluation.2.Through the simulation of the excavation construction process of the mountain tunnel,the stress state of the tunnel structure and the displacement change during the construction process are obtained,and the health status and safety of the tunnel structure during the construction period were preliminarily evaluated.Combined with the engineering practice,the influence of support timing and deformation pressure on the safety of tunnel structure during the construction was analyzed to ensure the safety of construction.Based on the non-continuous contact model of the nonlinear contact principle,the deterioration process of the tunnel segment structure under long-term water and soil pressure was simulated.The safety evaluation criteria of the tunnel structure which was based on the joint opening of the segment were established.A preliminary safety assessment was made on the health of the segment structure at the typical location.Based on the mechanical analysis model of the reinforced concrete bond-slip principle,the failure process of the tunnel lining structure under long-term water and soil pressure was simulated,and the tunnel structure safety evaluation criteria based on the section bending moment and axial force were established.A preliminary safety assessment was made on the health status of the tunnel main structure at the typical location.3.Through the numerical simulation model of the tunnel structure with defects,based on the analysis and comparison of structure forces and deformations,combined with literature research,the influence of different defect degrees and defect locations on the tunnel structure was determined,and the safety evaluation criteria in the defect state were established.4.Based on fuzzy comprehensive evaluation method,a tunnel structure safety evaluation system was established to evaluate the safety of the tunnel.The health state of the tunnel structure was divided into four grades.For the mountain tunnel,the weighting value of each influencing factor was calculated by the analytic hierarchy process.The membership function of each factor in the indicator layer was established.This method was used in the actual engineering and it showed that the final assessment result of the tunnel structure safety was level III,and the structure was in a potentially unsafe state.