In-situ calibrated deformation reconstruction method for fiber Bragg grating embedded smart Geogrid

To fulfill the requirement of deformation measurement using Fiber Bragg Grating (FBG) embedded smart Geogrid in practical civil engineering related applications, the in-situ calibrated deformation reconstruction method has been studied, which is capable of improving the accuracy and reducing the amount of embedded FBGs. The fabricating technology of the FBG embedded smart Geogrid has been briefly introduced first and this is followed by the experimental studies on the strain and temperature sensing characteristics of the smart Geogrid. Then, the in-situ calibrated reconstructing method has been elaborated, which used an external sensor to provide a reference displacement and adopted Linear Descending Inertia Weight Particles Swarm Optimization (LDIW-PSO) algorithm to determine the optimal weighted coefficient so as to calibrate the reconstructed deformation. The linear interpolation based scenario for reducing the amount of FBGs has been discussed. For the purpose of validating the superiority of the proposed reconstruction method, the Finite Element (FE) simulations as well as experiments were performed to compare the performances of the in-situ calibrated reconstructing methods (with both full FBG nodes and reduced FBG nodes) with those of the existing basic reconstruction method. Both the simulating and experimental results indicate that the in-situ calibrated method (full FBG nodes) provides highest accuracy, and the in-situ calibrated method (reduced FBG nodes) is able to improve the accuracy as well as reduce the amount of FBGs required for calculation. Therefore, the proposed in-situ calibrated method fits the practical applications in which the long Geogrid are deployed for the reinforcement and deformation evaluation of the large-scale geological structures. Overall, the in-situ calibrated deformation reconstructing method for the FBG embedded smart Geogrid method is promising for the practical applications, and it is advisable to select suitable reconstruction methods as per the requirements of civil engineering.