New fiber bragg grating (Fbg)-based device for measuring small and large radial strains in triaxial apparatus

Wen Bo Chen, Wei Qiang Feng, Jian Hua Yin, Jie Qiong Qin

Research output: Journal article publicationComment/debate/erratum

10 Citations (Scopus)


In triaxial tests, it is of great importance to accurately measure the radial strain of a specimen. However, devices for radial strain measurement are relatively fewer than the ones for vertical strain measurement. In this study, a new measurement device based on the fiber Bragg grating (FBG) was developed to determine the small and large radial strains of a soil specimen. The new device includes two yokes and two compass-type mechanisms, which are mounted on diametrically opposite sides of the specimen. Metal strips bonded with FBG sensors were chosen as sensing elements and installed at two ends of two legs of a compass-type mechanism so that the small deformation of the specimen could be amplified by a constant ratio to a more detectable value with a higher signal–noise ratio. Considering the temperature sensitivity of FBG and the real working environment, the new device was carefully calibrated underwater. Validation tests on an intact triaxial specimen demonstrated that the new device can work reliably and accurately under both static and cyclic loadings.

Original languageEnglish
Pages (from-to)1059-1063
Number of pages5
JournalCanadian Geotechnical Journal
Issue number7
Publication statusPublished - Jul 2021


  • Cyclic
  • Fiber Bragg grating (FBG)
  • Radial strain
  • Small strain measurement
  • Triaxial test

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Geotechnical Engineering and Engineering Geology


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