Diagnosis Method Of Uneven Settlement Of Metro Tunnel Based On BOTDA Technique

Uneven settlement of structure is one of the main diseases in the operation of Metro tunnels.How to effectively diagnose the uneven settlement of long-distance metro tunnels is still a challenging problem.In order to solve this problem,a BOTDA-based diagnosis method for uneven settlement of metro tunnels is studied by using the strain monitoring information of high-density measurement points in the whole line of the tunnel provided by distributed Brillouin optical fiber sensing technology.The main characteristics of distributed optical fiber sensing technology are briefly discussed,and the research level of BOTDA-based distributed optical fiber sensing technology in measuring distance and accuracy is further summarized.The main causes of uneven settlement of metro tunnels are summarized comprehensively,and the existing main monitoring methods for the disease of uneven settlement of metro tunnels are described in detail.The calculation method of longitudinal strain of metro tunnel structure based on BOTDA technology is introduced in detail.From this,the main body of this paper,namely the longitudinal strain data of metro tunnel structure,is obtained.According to the non-linear characteristics of strain monitoring,the classification method of support vector machine is used to classify the longitudinal strain data of the measured points of metro tunnel structure.Based on the classification results,a diagnosis algorithm for the uneven settlement of Metro Tunnel Based on the longitudinal strain is proposed.Emphasis is laid on the numerical validation of the proposed diagnostic algorithm for non-uniform settlement of Metro tunnel.Taking a metro tunnel as an example,the finite element model of the metro tunnel is established by using ANSYS finite element analysis software.By simulating the damage condition of non-uniform settlement of Metro tunnel,the influence of non-uniform settlement of Metro Tunnel on longitudinal strain data of tunnel structure is discussed.The validity of the proposed diagnostic algorithm for uneven settlement of metro tunnels based on longitudinal strain angle is verified by using the results of finite element model of Metro tunnels,and the influence of noise on the diagnostic results of the proposed algorithm is analyzed.Taking a practical project as an example,the wiring scheme and construction scheme of distributed sensing optical fibers for a subway project in Jinan are introduced in detail.Based on the symmetry of distributed sensing optical fibers,the strain curve of characteristic points is studied,which verifies the rationality of strain monitoring data.The classification results of measured data are briefly analyzed,and the longitudinal strain data of the measured points are substituted for the corresponding diagnosis algorithm of uneven settlement of metro tunnels to diagnose.The visualization of the diagnosis structure of metro tunnels is realized.