Open AccessApplication of optical-fiber sensing to concrete support and continuous wall strain monitoring
Author(s) -
Junqiang Qi,
Baojun Wang,
Xing Wang,
Zhanpu Song,
Zhijiu Cui
Publication year - 2019
Publication title -
iop conference series. earth and environmental science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.179
H-Index - 26
eISSN - 1755-1307
pISSN - 1755-1315
DOI - 10.1088/1755-1315/349/1/012032
Subject(s) - inclinometer , optical fiber , fiber optic sensor , structural health monitoring , structural engineering , data acquisition , optical time domain reflectometer , displacement (psychology) , geotechnical engineering , materials science , engineering , computer science , geology , polarization maintaining optical fiber , psychology , telecommunications , geodesy , psychotherapist , operating system
Optical-fiber sensing technologies are being theoretically and practically researched. These technologies, possessing linear and real-time properties, realize the sectional analysis of strain and temperature and improve point monitoring methods in deep foundation pit supporting systems. In this paper, a field experimental model of the deep foundation pit supporting system was designed in the subway station in Suzhou, China, which utilizes optical-fiber sensing technology. In this field experiment, conventional monitoring methods, namely steel-bar meters, inclinometer, and water-level observation hole were firstly employed for comparative study. Distributed optical-fiber sensors (DOFS) were employed at the same time based on Brillouin optical time-domain analysis (BOTDA). The experimental results show that the DOFS can more comprehensively monitor the pit support system than the conventional methods. The fiber sensors data reflect the positive and negative strain distribution of the walls in a linear section and detect a leakage by analyzing abnormal data. The fiber sensors data response a linear increase of the axial strain with excavation depth, and a bending phenomenon is discovered by the data curves because of the excavation depth difference of the testing support. With temperature compensation, the fiber monitoring data are more accurate to the excavation result than the steel-bar does. Thus, the sensors can get a combined action function of steel-bar which used for testing axial force and temperature, inclinometer which used for testing wall horizontal displacement, and water-level observation holes with accurately monitoring data.