An optical fibre monitoring system for evaluating the performance of a soil nailed slope

  • Zhu, Hong-Hu ;
  • Ho, Albert N.L. ;
  • Yin, Jian-Hua ;
  • Sun, H.W. ;
  • Pei, Hua-Fu ;
  • Hong, Cheng-Yu
  • Received : 2010.10.11
  • Accepted : 2012.03.03
  • Published : 2012.05.25


Conventional geotechnical instrumentation techniques available for monitoring of slopes, especially soil-nailed slopes have limitations such as electromagnetic interference, low accuracy, poor longterm reliability and difficulty in mounting a series of strain sensors on a soil nail bar with a small-diameter. This paper presents a slope monitoring system based on fibre Bragg grating (FBG) sensing technology. This monitoring system is designed to perform long-term monitoring of slope movements, strains along soil nails, and other slope reinforcement elements. All these FBG sensors are fabricated and calibrated in laboratory and a trial of this monitoring system has been successfully conducted on a roadside slope in Hong Kong. As part of the slope stability improvement works, soil nails and a toe support soldier-pile wall were constructed. During the slope works, more than 100 FBG sensors were installed on a soil nail, a soldier pile, and an in- place inclinometer. The paper presents the layout and arrangement of the instruments as well as the installation procedures adopted. Monitoring data have been collected since March 2008. This trial has demonstrated the great potential of the optical fibre monitoring system for long-term monitoring of slope performance. The advantages of the slope monitoring system and experience gained in the field implementation are also discussed in the paper.


optical fibre sensing;soil nailing;slope monitoring system;fibre Bragg grating (FBG);geotechnical instrumentation


  1. Ding, X.L., Huang, D.F., Yin, J.H., Chen, Y.Q., Lau, C.K., Yang, Y.W., Sun, Y.R., Chen, W. and He, X.F. (2003), "Development and field testing of a multi-antenna GPS system for deformation monitoring", Wuhan Univ. J. Nat. Sci., 8(2), 671-676.
  2. Dunnicliff, J. (1993), Geotechnical instrumentation for monitoring field performance, John Wiley & Sons Inc, New York.
  3. Fredlund, D.G. and Rahardjo, H. (1993), Soil mechanics for unsaturated soils, John Wiley & Sons Inc, New York.
  4. Kersey, A.D., Davis, M.A., Patrick, H.J., LeBlanc, M., Koo, K.P. Askins, C.G., Putnam, M.A. and Friebele, E.J. (1997), "Fiber grating sensors", J. Lightwave Technol., 15(8), 1442-1463.
  5. Gasmo, J., Hritzuk, K.J., Rahardjo, H. and Leong, E.C. (1999), "Instrumentation of an unsaturated residual soil slope", Geotech. Test. J., 22(2), 128-137.
  6. Hill, K.O., Fujii, Y., Johnson, D.C. and Kawasaki, B.S. (1978), "Photosensitivity in optical fiber waveguides: application to reflection filter fabrication", Appl. Phys. Lett., 32(10), 647-649.
  7. Ho, Y.T., Huang, A.B. and Lee, J.T. (2006), "Development of a fibre Bragg grating sensored ground movement monitoring system", Meas. Sci. Technol., 17(7), 1733-1740.
  8. Inaudi, D. (1997), Fiber optic sensor network for the monitoring of civil engineering structures, PhD Thesis, EPFL, Lausanne, Switzerland.
  9. Li, A.G., Yue, Z.Q., Tham, L.G., Lee, C.F. and Law, K.T. (2005), "Field-monitored variations of soil moisture and matric suction in a saprolite slope", Can. Geotech. J., 42(1), 13-26.
  10. Lin, C.P. and Tang, S.H. (2005). "Development and calibration of a TDR extensometer for geotechnical monitoring", Geotech. Test. J., 28(5), 1-8.
  11. Millis, S.W., Ho, A.N.L., Chan, E.K.K., Lau, K.W.K. and Sun, H.W. (2008), "Instrumentation and real time monitoring of slope movement in Hong Kong", Proceedings of the12th International Conference of International Association for Computer Methods and Advances in Geomechanics, Goa, India.
  12. Morey, W.W., Meltz, G. and Glenn, W.H. (1989), "Fiber optic bragg grating sensors", Proceedings of the SPIE.
  13. Ng, C.W.W., Zhan, L.T., Bao, C.G., Fredlund, D.G. and Gong, B.W. (2003), "Performance of an unsaturated expansive soil slope subjected to artificial rainfall infiltration", Geotechnique, 53(2), 143-157.
  14. Peyret, M., Djamour, Y., Rizza, M., Ritz, J.F., Hurtrez, J.E., Goudarzi, M.A., Nankali, H., Chery, J., Le Dortz, K. and Uri, F. (2008), "Monitoring of the large slow Kahrod landslide in Alborz mountain range (Iran) by GPS and SAR interferometry", Eng. Geol., 100(3-4), 131-141.
  15. Wong, H.N., Ho, K.K.S. and Sun, H.W. (2006), "The role of slope instrumentation in landslide risk management- Hong Kong experience", Proceedings of the Conference on Landslide, Sinkhole, Ipoh, Malaysia.
  16. Yin, J.H., Ding, X.L., Yang, Y.W., Lau, C.K., Huang, D.F. and Chen, Y.Q. (2004), "Integration of conventional instruments and global positioning system for automatic monitoring of slopes", Chin. J. Rock Mech. Eng., 23(3), 357-364. (in Chinese)
  17. Yoshida, Y., Kashiwai, Y., Murakami, E., Ishida, S. and Hashiguchi, N. (2002), "Development of the monitoring system for slope deformations with fiber Bragg grating arrays", Proceedings of the SPIE.
  18. Zhang, T.L.T., Ng, C.W.W. and Fredlund, D.G. (2006), "Instrumentation of an unsaturated expansive soil slope", Geotech. Test. J., 30(2), 1-11.

Cited by

  1. Experimental investigation of pavement behavior after embankment widening using a fiber optic sensor network vol.14, pp.1, 2015,
  2. Experimental study on pullout performance of sensing optical fibers in compacted sand vol.73, 2015,
  3. Fiber Bragg grating-based performance monitoring of a slope model subjected to seepage vol.23, pp.9, 2014,
  4. Acceleration Characteristics of a Rock Slide Using the Particle Image Velocimetry Technique vol.2016, 2016,
  5. Blind Source Separation Model of Earth-Rock Junctions in Dike Engineering Based on Distributed Optical Fiber Sensing Technology vol.2015, 2015,
  6. Experiment study on constraint condition of distributed sensing optical fiber in deformation measure of soil vol.61, 2017,
  7. Techno-economical and practical considerations for SHM systems vol.7, pp.2, 2017,
  8. Application of FBG Sensing Technology in Stability Analysis of Geogrid-Reinforced Slope vol.17, pp.3, 2017,
  9. Slope Stability Analysis Based on Measured Strains along Soil Nails Using FBG Sensing Technology vol.2013, 2013,
  10. FBG-Based Monitoring of Geohazards: Current Status and Trends vol.17, pp.3, 2017,
  11. Performance evaluation of soil-embedded plastic optical fiber sensors for geotechnical monitoring vol.17, pp.2, 2016,
  12. A Study on Distribution Measurement and Mechanism of Deformation due to Water Loss of Overburden Layer in Vertical Shaft vol.2015, 2015,
  13. Interfacial characterization of soil-embedded optical fiber for ground deformation measurement vol.23, pp.9, 2014,
  14. Deformation reconstruction of a smart Geogrid embedded with fiber Bragg grating sensors vol.26, pp.12, 2015,
  15. Three dimensional seismic and static stability of rock slopes vol.8, pp.1, 2015,
  16. Introduction to an FBG-based inclinometer and its application to landslide monitoring vol.5, pp.5, 2015,
  17. Model testing of the response of stabilizing piles in landslides with upper hard and lower weak bedrock vol.204, 2016,
  18. Distributed acquisition, characterization and process analysis of multi-field information in slopes vol.182, 2014,
  19. A novel optimal plane arrangement of stabilizing piles based on soil arching effect and stability limit for 3D colluvial landslides vol.195, 2015,
  20. Quantitative Sensitivity Analysis of Surface Attached Optical Fiber Strain Sensor vol.14, pp.6, 2014,
  21. Quantitative Evaluation of Optical Fiber/Soil Interfacial Behavior and Its Implications for Sensing Fiber Selection vol.15, pp.5, 2015,
  22. Internal Deformation Monitoring of Slope Based on BOTDR vol.2016, 2016,
  23. Application ofR/SMethod for Dynamic Analysis of Additional Strain and Fracture Warning in Shaft Lining vol.2015, 2015,
  24. Numerical modeling of soil nail walls considering Mohr Coulomb, hardening soil and hardening soil with small-strain stiffness effect models vol.6, pp.4, 2014,
  25. Study of Three-Component FBG Vibration Sensor for Simultaneous Measurement of Vibration, Temperature, and Verticality vol.2015, 2015,
  26. Reliability of long-term monitoring data vol.4, pp.1, 2014,
  27. Evaluations of load-deformation behavior of soil nail using hyperbolic pullout model vol.6, pp.3, 2014,
  28. Monitoring and analysis of PHC pipe piles under hydraulic jacking using FBG sensing technology vol.49, 2014,
  29. Study on the Deformation Measurement of the Cast-In-Place Large-Diameter Pile Using Fiber Bragg Grating Sensors vol.17, pp.3, 2017,
  30. A preliminary study on the location of the stabilizing piles for colluvial landslides with interbedding hard and soft bedrocks vol.224, 2017,
  31. Smart Sensing Technologies and Their Applications in Civil Infrastructures 2016 vol.2016, 2016,
  32. Mechanical behaviors of SD and CFA piles using BOTDA-based fiber optic sensor system: A comparative field test study vol.104, 2017,
  33. Evaluation of feature- and pixel-based methods for deflection measurements in temporary structure monitoring vol.5, pp.5, 2015,
  34. Application of Distributed Optical Fiber Sensing Technology in the Anomaly Detection of Shaft Lining in Grouting vol.2015, 2015,
  35. Development and Application of Smart Geogrid Embedded with Fiber Bragg Grating Sensors vol.2015, 2015,
  36. Distributed fiber optic monitoring and stability analysis of a model slope under surcharge loading vol.11, pp.4, 2014,
  37. Research on Joint Parameter Inversion for an Integrated Underground Displacement 3D Measuring Sensor vol.15, pp.12, 2015,
  38. Using Custom Fiber Bragg Grating-Based Sensors to Monitor Artificial Landslides vol.16, pp.12, 2016,
  39. Application of FBG sensors for geotechnical health monitoring, a review of sensor design, implementation methods and packaging techniques vol.244, 2016,
  40. Investigation of the evolutionary process of a reinforced model slope using a fiber-optic monitoring network vol.186, 2015,
  41. Collapse mechanism for deep tunnel subjected to seepage force in layered soils vol.8, pp.5, 2015,
  42. Deformation Monitoring of Geomechanical Model Test and Its Application in Overall Stability Analysis of a High Arch Dam vol.2015, 2015,
  43. Distributed Measurement of Temperature for PCC Energy Pile Using BOFDA vol.2015, 2015,
  44. Influences of Initial Water Content and Roughness on Skin Friction of Piles Using FBG Technique vol.17, pp.4, 2017,
  45. The Mechanical Performance of Shear Key of Immersed Tube Tunnel with Differential Foundation Settlement vol.2016, 2016,
  46. Review: optical fiber sensors for civil engineering applications vol.48, pp.4, 2015,
  47. Development and application of a fixed-point fiber-optic sensing cable for ground fissure monitoring vol.6, pp.4, 2016,
  48. Displacement Parameter Inversion for a Novel Electromagnetic Underground Displacement Sensor vol.14, pp.12, 2014,
  49. Development of a preliminary slope stability calculation method based on internal horizontal displacements vol.15, pp.5, 2018,
  50. A monitoring and warning system for expressway slopes using FBG sensing technology vol.14, pp.5, 2018,
  51. Improved plane layout of stabilizing piles based on the piecewise function expression of the irregular driving force vol.15, pp.4, 2018,
  52. Fiber Bragg grating sensor-based monitoring strategy for slope deformation in centrifugal model test pp.0260-2288, 2018,