MONITORING DEFORMATION AND DAMAGE ON ROCK STRUCTURES WITH DISTRIBUTED FIBER OPTICAL SENSING

J. Chai, S.M. Wei, X.T. Chang, J.X. Liu
College of Energy Science and Engineering, Xi’an University of Science and Technology,China

Int. J. Rock Mech. Min. Sci. Vol. 41, No. 3


Abstract: This paper elaborates the application of fiber optic al sensors for monitoring rock structures to provide an internal measurement. Recent structural failure and damage associated with earthquakes, pipeline ruptures, and railroad bridge barge impact, have underscored the need for structural integrity monitoring systems using distributed fiber optical fiber sensors. The fiber optical sensor has potential advantages for the safe monitoring sensor of structures: (i) unlimited length of gage, (ii) applicability to dynamic measurement, and (iii) less affected by temperature. To find the relationship between the bending loss of fiber and the changeable characteristic and premonitory information during the course of the beginning and developing of rock damage, a distributed optical fiber sensing technique based on the optical time domain reflectometer (OTDR) is presented in this paper, and a new sensor designed. By the simulation experiment with analogy material for mining, the sensor is embedded in the rock layer of the model. And the theory and technology for detecting rock failure, and the interaction mechanism of the fiber with the material are studied.


Key Words: Simulation experiment; Rock deformation and damage; Distributed fiber optical sensing; OTDR; Snakelike fiber optical sensor (SFOS); Bending loss


REFERENCES

[1] E. Udd and John Paul Theriault. Microbending fiber optic sensors for smart structures[C]. Proc. SPIE 1990:1170:478-482

[2] Wanser , Voss .Crack detection using multimode fiber optical time domain reflectometry[C].Proc.SPIE 1994:2294:43-52

[3] Chuan Li, Yi-mo Zhang, Tie-gen Liu, Xin Li, Xi-ming Cheng. Distributed optical fiber bidirectional strain sensor for gas trunk pipelines[J]. Optics and Lasers in Engineering. 2001: 36:41-47

[4] Ansari f. Real-Time condition monitoring of concrete structures by embedded optical fibers, in nondestructive testing of concrete elements and structure[C]. Proceedings of the ASCE, San
Antonio, TX, APRIL 1992.pp.49-59

[5] A. Mendez and T. F. Morse. Overview of optical fiber sensors embedded in concrete [C]. Proc. SPIE 1992:Vol.1798:205-216

[6] Liu Haowu, Yang Zhaohui. Distributed optical fiber sensing of cracks in concrete [C]. Proc. SPIE 1998:3555:291-299

[7] Griffiths R W. Structural integrity monitoring of bridges using fiber optics[C]. Proc. SPIE 1995, Vol.2446: 127-139

[8] A. Mendez and T.F. Morse. Application of embedded optical fiber sensors in reinforced concrete building and structures[C]. SPIE Proceedings, Fiber Optic Smart Structures and Skins 1989:Vol.1170: 60-69

[9] K. F. Voss and K. H. Wanser. Fiber sensors for monitoring structural strain and cracks[C]. 2nd European Conf. On Smart Structures and Materials (ECSSM 2), Glasgow, Scotland. Oct.
:12-14 (1994)

[10] Dakin J. Distributed optical fiber sensors[C]. Proc. SPIE 1992: 1797:76-108

[11] Fei Luo, Jingyuan Liu , Naibing Ma , T.F. Morse. A fiber optic microbend sensor for distributed sensing application in the structural strain monitoring [J]. Sensors and Actuators, 75
(1999): 41-44

[12] CAI DE-suo, HE Xing-ji, ZHANG Ling. Distributed optical fiber sensing technology for crack detection in the small scale plaster model test of arch dam [J]. SHUI LI XUE BAO, China
, 2001,(2):50-54

[13] Chai Jng. Basic study on crack and deflection of rock by optical fiber sensing technology. Ph.D. thesis. Xi’an University of Science and Technology, Xi’an, China, 2003