Novel FBG-Based Effective Stress Cell for Direct Measurement of Effective Stress in Saturated Soil
Publication: International Journal of Geomechanics
Volume 20, Issue 8
Abstract
In this study, a novel effective stress cell based on fiber Bragg grating (FBG) sensing technology is developed for direct measurement of effective stress in saturated soil. The primary concept of direct measurement is that the pore-water pressures acting on both front and back surfaces of the sensing plate do not induce the deflection of the sensing plate, and thus the measured deflection of the sensing plate is caused by the effective stress only. The calibration results of the FBG-based effective stress cell (FBG-ESC) demonstrate a good linearity between the Bragg wavelength of the FBG sensor and the applied pressure. The workability and performance of the FBG-ESC in a saturated soil have been verified in a physical model test subjected to vertical pressures. It is found that the effective stress data directly measured by the FBG-ESC agree well with the effective stress values calculated, according to the effective stress principle, from the difference between the total stress and pore-water pressure measured by conventional transducers. All these results indicate that the novel FBG-ESC is capable of directly measuring the effective stress in a saturated soil.
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Acknowledgments
The work in this paper is supported by an ITF project (Grant No.: ITS/049/13), a CRF project (Grant No.: PolyU 12/CRF/13E) from the Research Grants Council (RGC) of Hong Kong Special Administrative Region Government (HKSARG) of China, two GRF projects (PolyU 152796/16E, PolyU 152209/17E) from RGC of HKSARG of China. The authors also acknowledge the financial supports from the Research Institute for Sustainable Urban Development of the Hong Kong Polytechnic University and grants (1-BBAG, 1-ZVEF, 1-ZVEH, 4-BCAW, 5-ZDAF, G-YBHQ, G-YN97) from the Hong Kong Polytechnic University.
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Published In
International Journal of Geomechanics
Volume 20 • Issue 8 • August 2020
Copyright
© 2020 American Society of Civil Engineers.
History
Received: Feb 17, 2019
Accepted: Jan 16, 2020
Published online: May 20, 2020
Published in print: Aug 1, 2020
Discussion open until: Oct 20, 2020
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