| Deformation field is one of the most intuitive parameters used to characterize the safety state of tunnel during construction and operation.Conventional point-type deformation measurement technology can only obtain deformation information of sensor arrangement position,and can not obtain deformation field information such as tunnel floor settlement and section convergence with continuous time and space.Distributed fiberoptic sensing technology is characterized by its soft material and wide measuring range.It is easy to stick or build into the matrix material to sense the strain along the length of the optical fiber.Distributed strain data obtained can reconstruct the overall deformation of the base material and provide an effective means for wide-range measurement of deformation fields such as floor settlement and convergence of the section of the tunnel.However,due to the large area and long distance measured,serious cumulative error exists in the measurement of deformation field,which affects the accurate monitoring of tunnel deformation field.In view of the above problems,this paper studies the key technologies of tunnel safety monitoring based on fiber optic smart sensor belt,the main research contents and contributions are as follows:(1)In response to the serious impact of cumulative errors in the settlement of the bottom plate of long-distance tunnels on the accuracy of deformation field measurement,a correction method for cumulative errors in tunnel settlement deformation based on typical error matching is proposed.Based on typical deformation modes of tunnel settlement,a typical error library for prediction and expansion based on existing data is established by analyzing the variation law of cumulative error curves under typical settlement modes.The matching function suitable for various data density scatter curves has been designed with emphasis,solving the problem of automatic matching between the deformation to be corrected and the settlement mode type in the error library.Furthermore,adaptive correction of the reconstructed deformation field has been carried out based on different typical settlement modes,improving the measurement accuracy of the tunnel settlement deformation field.On this basis,the system conducted simulation and indoor experiments to verify the effectiveness and accuracy of the above methods.(2)Under the complex load of a tunnel,its circumferential contour deformation varies in both horizontal and vertical directions,making it difficult to unify the cumulative error variation law and typical deformation modes.In this regard,the in-situ correction method of tunnel circumferential deformation cumulative error based on the dip angle information of key points is studied.The dip angle information of key points is obtained through high-precision tilt sensors additionally installed in the fiber optic smart sensor belt.Based on this,the particle swarm optimization is used to in-situ correct the circumferential deformation field reconstructed by the sensing belt,so as to reduce the measurement cumulative error of tunnel circumferential deformation field.The experimental results show that this method can significantly improve the reconstruction accuracy of tunnel circumferential deformation and provide the contour of tunnel circumferential deformation.(3)The software for Fiber optic monitoring and error self-correction software for tunnel deformation fields has been developed.Based on the MVC(Model View Controller)framework,the software has embedded the deformation field reconstruction algorithm and cumulative error correction method.The deformation display module,automatic correction module,data comparison module,data storage module,etc.have been designed to realize the single and multiple display of the deformation of the sensing belt in tunnel Deformation monitoring,and the automatic correction of cumulative error The functions of displacement calculation,data comparison,and historical review have effectively improved the processing efficiency of monitoring data. |
