Fiber Bragg grating sensors for subgrade deformation monitoring in seasonally frozen regions

Abstract

Summary Excessive subgrade permanent deformation resulting from heavy vehicle traffic and freezing–thawing cycles is one of the primary causes of road damage in seasonally frozen regions. In this paper, an implanted cantilever sensing beam based on fiber Bragg gratings (FBGs) is proposed for subgrade deformation monitoring. Two optical fibers with inscribed FBGs were adhered to the opposite external sides of a PVC pipe which was selected as substrate. After laboratory calibration tests, the cantilever sensing beam was installed horizontally through the subgrade of a testing section. The beam will be bended driven by the deformation of the soils under the action of vehicles, and the deformation is recorded by the FBGs and calculated through principles of continuum mechanics. The subgrade deformation is considered to be the deflection of the sensing beam. The feasibility of the developed method was validated based on the results of field testing conducted for a three‐year period. It has been found that the combination of freezing–thawing cycles with heavy vehicle loading magnifies the extent of permanent subgrade deformation. The developed FBG‐based implanted cantilever sensing beams are thereby demonstrated to provide a feasible and effective approach for the in situ monitoring of subgrade deformation.

Implementation of a Mobile Platform Based on Fiber Bragg Grating Sensors for Automotive Traffic Monitoring

“…Realizing field tests concerning the application of Fiber Bragg Grating sensors is of crucial importance for the monitoring of both railways [10,11] and roads [12][13][14]. Even though research regarding fiber-based weigh-in-motion systems has been reported over the last 20 years, none of these references offer a quantitative analysis about weight measurements in the form of a final product that conforms to transportation regulations [15,16].…”

Fiber Bragg Grating Sensors for Pile Jacking Monitoring in Clay Soil

“…The spectral width of the grating period Λ is in the range 0.05–0.3 nm, and all other ordinary light passes through the optical fiber grating [ 23 ]. The Bragg wavelength λ B satisfies Bragg conditions [ 24 ]: where is the effective refractive index of the optical fiber core.…”

Numerical and experimental analysis of the reliability of strain measured by surface‐mounted fiber‐optic sensors based on Bragg gratings

“…This is largely related to the greater availability and relative cheapness of equipment that registers physical signals from these sensors. The advantages of FOSS based on Bragg gratings and typical schemes for their application are widely covered in the literature, in particular in previous papers 1–4 . In a number of works, the results of measurements recorded with FOSS based on Bragg gratings are compared with data obtained by other strain measurement systems 5–8 …”

“…The advantages of FOSS based on Bragg gratings and typical schemes for their application are widely covered in the literature, in particular in previous papers. [1][2][3][4] In a number of works, the results of measurements recorded with FOSS based on Bragg gratings are compared with data obtained by other strain measurement systems. [5][6][7][8] It is necessary to have estimates of the reliability of the strain measurement results when using any sensors, including FOSS based on Bragg gratings.…”