Structural Condition Diagnosis Of Underpass Railway Tunnel Based On Longitudinal Multi-Section Strain Correlation

Urban railway tunnels has some limitations in using conventional tunnel detection technology to diagnose,and it is impossible to achieve long-distance distributed multi-period monitoring.In order to solve this problem,the long-distance distributed Brillouin optical fiber is used as the strain sensor of tunnel.A method of structural state diagnosis of railway tunnel under railway based on curvature correlation of longitudinal multi-section of tunnel is proposed,and its application in actual tunnel is studied.This paper systematically summarizes the research achievements and development trends of monitoring measurement and damage diagnosis of tunnels at home and abroad,and focuses on the relevant methods and theories of structural state diagnosis of tunnels using long-distance distributed sensing technology.On this basis,the basic principle of the relationship between the curvature and the strain of tunnel structure is studied,and the influence of shear on the relationship between the strain and curvature of tunnel is studied with the idea of energy method.That is to say,under what conditions can the influence of shear on the relationship between the strain and the curvature of tunnel be neglected,and the influence of shear and bending moment on the relationship between the strain and the curvature of tunnel is studied by Verification is carried out.Based on the engineering background of Liuchangshan Road Tunnel,the reasonable parameters of surrounding rock and tunnel structure are deter mined,and the finite element model of Liuchangshan Road Tunnel is established.By means of numerical simulation,the relationship model between structural strain and curvature of Liuchangshan Road tunnel under healthy condition is constructed.Based on the model of the relationship between strain and curvature of Liu Changshan Road tunnel,a method for damage diagnosis of tunnel structure based on curvature correlation is proposed by selecting the characteristic section of tunnel and combining with the idea of artificial neural network.Taking the example of finite element simulation of tunnel structure damage,the reliability of the proposed method under different noise levels is analyzed,and the method of tunnel structure damage diagnosis based on curvature correlation is validated.According to the proposed method of tunnel structural damage diagnosis,based on the actual tunnel longitudinal multi-section strain monitoring data,the structural state diagnosis of Liuchangshan Road tunnel is carried out.The results show that the damage diagnosis method based on curvature correlation of tunnel structure is effective,and can maintain the reliability of the diagnosis results at a certain noise level,and then effectively diagnose the damage of the actual tunnel structure.The damage diagnosis method of tunnel structure based on curvature correlation established in this paper is suitable for solving the problem of multi-section damage location diagnosis of actual tunnel structure under railway.