An evaluation of primary lining deformation using measurements with FBG sensors during a tunnel excavation

The paper presents an evaluation of data gathered with the FBG (Fiber Bragg Gratings) instrument for primary lining deformation measurement, which was installed into primary lining of adit during construction. The evaluation is related to the initial shape of primary lining, and its deflection curve is computed. Definition of appropriate boundary conditions can be verified with the use of geodetic convergence monitoring results. The developed evaluation procedure can be used also for determination of Bragg wavelengths during the design of primary lining monitoring.