Feasibility study of anchored fiber-optic strain-sensing arrays for monitoring soil deformation beneath model foundation

Cheng-Cheng Zhang1,2, Hong-Hu Zhu1,*, Dong-Dong Chen1, Xing-Yu Xu1, Bin Shi1, Xiao-Ping Chen3 

1School of Earth Sciences and Engineering, Nanjing University, Nanjing, Jiangsu 210023, China

2Department of Civil and Environmental Engineering, University of California, Berkeley, Berkeley, CA 94720

3MOE Key Laboratory of Disaster Forecast and Control in Engineering, College of Science and Engineering, Jinan University, Guangzhou, Guangdong 510632, China

Geotechnical Testing Journal, 2018.

Abstract: High-accuracy deformation measurement is an essential part of geotechnical model testing, in which fiber-optic sensors have great potentialities. In this study, a 1g plane-strain model test was performed to investigate the feasibility of using fiber Bragg grating (FBG) strain-sensing arrays for monitoring soil deformation beneath a strip footing. The FBG array with specially-made anchors was designed to enhance the fiber–soil interfacial bond and, hence, to improve the measurement quality. Three arrays were embedded horizontally within the soil to monitor internal linear strains, while digital photography-based particle image velocimetry (PIV) was employed to obtain superficial displacement and strain fields. Test results show that the strains captured by FBGs were comparable with equivalent strains determined via PIV analyses in terms of strain development, which reflected the evolution of soil deformation under incremental loads. Finally, the benefits and drawbacks of anchored FBG arrays for monitoring laboratory-scale models were discussed, with the conclusion being that they are capable of capturing internal strains or a strain profile of soil with low noise and high resolution, but there has to be a trade-off between robustness and sensitivity.

Keywords: fiber Bragg grating (FBG); strip footing; strain measurement; particle image velocimetry (PIV); fiber-optic sensor

References

Abu-Farsakh, M., Chen, Q., Sharma, R., and Zhang, X., 2008, “Large-scale model footing tests on geogrid-reinforced foundation and marginal embankment soils,” Geotech. Test. J., Vol. 31, No. 5, p. 101465, http://dx.doi.org/10.1520/GTJ101465

ASTM F3079-14, 2014, Standard Practice for Use of Distributed Optical Fiber Sensing Systems for Monitoring the Impact of Ground Movements During Tunnel and Utility Construction On Existing Underground Utilities, ASTM International, West Conshohocken, PA, www.astm.org

Cocjin, M. and Kusakabe, O., 2013, “Centrifuge observations on combined loading of a strip footing on dense sand,” Géotechnique, Vol. 63, No. 5, pp. 427–433, http://dx.doi.org/10.1680/geot.11.P.075

Damiano, E., Avolio, B., Minardo, A., Olivares, L., Picarelli, L., and Zeni, L., 2017, “A laboratory study on the use of optical fibers for early detection of pre-failure slope movements in shallow granular soil deposits,” Geotech. Test. J., Vol. 40, No. 4, pp. 529–541, http://dx.doi.org/10.1520/GTJ20160107

Das, B. M., 2010, Principles of Geotechnical Engineering (7th Edition), Cengage Learning, Stamford, CT, USA.

Doherty, P., Igoe, D., Murphy, G., Gavin, K., Preston, J., McAVOY, C., Byrne, B. W., Mcadam, R., Burd, H. J., Houlsby, G. T., Martin, C. M., Zdravković, L., Taborda, D. M. G., Potts, D. M., Jardine, R. J., Sideri, M., Schroeder, F. C., Muir Wood, A., Kallehave, D., and Skov Gretlund, J, 2015, “Field validation of fibre Bragg grating sensors for measuring strain on driven steel piles,” Géotech. Lett., Vol. 5, No. 2, pp. 74–79, http://dx.doi.org/10.1680/geolett.14.00120

Hauswirth, D., Iten, M., Richli, R., and Puzrin, A.M., 2010, “Fibre optic cable and micro-anchor pullout tests in sand,” Physical Modelling in Geotechnics, Two Volume Set: Proceedings of the 7th International Conference on Physical Modelling in Geotechnics (ICPMG 2010), S. Springman, J. Laue, and L. Seward, Eds., CRC Press, FL, USA, pp. 337–342.

Hoepffner, R., 2008, “Distributed fiber optic strain sensing in hydraulic concrete and earth structures: Measuring theory and field investigations on dams and landslides,” Ph.D. thesis, Technische Universität München, Germany.

Hossain, M. S. and Fourie, A., 2013, “Stability of a strip foundation on a sand embankment over mine tailings,” Géotechnique, Vol. 63, No. 8, pp. 641–650, http://dx.doi.org/10.1680/geot.11.P.111

Huang, A.-B., Lee, J.-T., Ho, Y.-T., Chiu, Y.-F., and Cheng, S.-Y., 2012, “Stability monitoring of rainfall-induced deep landslides through pore pressure profile measurements,” Soils Found., Vol. 52, No. 4, pp. 737–747, http://dx.doi.org/10.1016/j.sandf.2012.07.013

Hussaini, S. K., Indraratna, B., and Vinod, J. S., 2015, “Application of optical-fiber Bragg grating sensors in monitoring the rail track deformations,” Geotech. Test. J., Vol. 38, No. 4, pp. 387–396, http://dx.doi.org/10.1520/GTJ20140123

Iten, M., 2011, “Novel applications of distributed fiber-optic sensing in geotechnical engineering,” Ph.D. thesis, ETH Zürich, Switzerland.

Lee, J.-T., Tien, K.-C., Ho, Y.-T., and Huang, A.-B., 2011, “A fiber optic sensored triaxial testing device,” Geotech. Test. J., Vol. 34, No. 2, p. 102825, http://dx.doi.org/10.1520/GTJ102825

Li, F., Zhu, H.-H., Zhang, C.-C., and Shi, B., 2017, “Experimental study on feasibility of fiber Bragg grating-based foundation deformation monitoring,” J. Zhejiang Univ. (Eng. Sci.), Vol. 51, No. 1, pp. 204–211. (in Chinese)

Lienhart, W., 2015, "Case studies of high-sensitivity monitoring of natural and engineered slopes,” J. Rock Mech. Geotech. Eng., Vol. 7, No. 4, pp. 379–384, http://dx.doi.org/10.1016/j.jrmge.2015.04.002

Madabhushi, S. S. C. and Haigh, S. K., 2015, “Investigating the changing deformation mechanism beneath shallow foundations,” Géotechnique, Vol. 65, No. 8, pp. 684–693, http://dx.doi.org/10.1680/geot.14.P.226

Mcmahon, B. T., Haigh, S. K., and Bolton, M. D., 2013, “Optimal displacement mechanisms beneath shallow foundations on linear-elastic perfectly plastic soil,” Géotechnique, Vol. 63, No. 16, pp. 1447–1450, http://dx.doi.org/10.1680/geot.13.T.002

Michalowski, R. L. and Shi, L., 2003, “Deformation patterns of reinforced foundation sand at failure,” J. Geotech. Geoenviron. Eng., Vol. 129, No. 5, pp. 439–449, http://dx.doi.org/10.1061/(ASCE)1090-0241(2003)129:6(439)

Olivares, L., Damiano, E., Greco, R., Zeni, L., Picarelli, L., Minardo, A., Guida, A., and Bernini, R., 2009, “An instrumented flume to investigate the mechanics of rainfall-induced landslides in unsaturated granular soils,” Geotech. Test. J., Vol. 32, No. 2, pp. 788–796, http://dx.doi.org/10.1520/GTJ101366

Othonos, A. and Kalli, K., 1999, Fiber Bragg Gratings: Fundamentals and Applications in Telecommunications and Sensing, Artech House, Boston, MA, USA.

Schenato, L., 2017, “A review of distributed fibre optic sensors for geo-hydrological applications,” Appl. Sci., Vol. 7, No. 9, p. 896, http://dx.doi.org/10.3390/app7090896

Schenato, L., Palmieri, L., Camporese, M., Bersan, S., Cola, S., Pasuto, A., Galtarossa, A., Salandin, P., and Simonini, P., 2017, “Distributed optical fibre sensing for early detection of shallow landslides triggering,” Sci. Rep., Vol. 7, p. 14686, http://dx.doi.org/10.1038/s41598-017-12610-1

Stanier, S. A., Blaber, J., Take, W. A., and White, D. J., 2016, “Improved image-based deformation measurement for geotechnical applications,” Can. Geotech. J., Vol. 53, No. 5, pp. 727–739, http://dx.doi.org/10.1139/cgj-2015-0253

Take, W. A., 2015., “Thirty-Sixth Canadian Geotechnical Colloquium: Advances in visualization of geotechnical processes through digital image correlation,” Can. Geotech. J., Vol. 52, No. 9, pp. 1199–1220, http://dx.doi.org/10.1139/cgj-2014-0080

Toyosawa, Y., Itoh, K., Kikkawa, N., Yang, J.-J., and Liu, F., 2013, “Influence of model footing diameter and embedded depth on particle size effect in centrifugal bearing capacity tests,” Soils Found., Vol. 53, No. 2, pp. 349–356, http://dx.doi.org/10.1016/j.sandf.2012.11.027

Vahedifard, F., and Robinson, J. D., 2016, “Unified method for estimating the ultimate bearing capacity of shallow foundations in variably saturated soils under steady flow,” J. Geotech. Geoenviron. Eng., Vol. 142, No. 4, p. 4015095, http://dx.doi.org/10.1061/(ASCE)GT.1943-5606.0001445

Wang, B., Li, K., Shi, B., and Wei, G., 2009, “Test on application of distributed fiber optic sensing technique into soil slope monitoring,” Landslides, Vol. 6, No. 1, pp. 61–68, http://dx.doi.org/10.1007/s10346-008-0139-y

Weng, X., Zhao, Y., Lou, Y., and Zhan, J., 2016, “Application of fiber Bragg grating strain sensors to a centrifuge model of a jacked pile in collapsible loess,” Geotech. Test. J., Vol. 39, No. 3, pp. 362–370, http://dx.doi.org/10.1520/GTJ20150076

White, D. J., Take, W. A., and Bolton, M. D., 2003, “Soil deformation measurement using particle image velocimetry (PIV) and photogrammetry,” Géotechnique, Vol. 53, No. 7, pp. 619–631, http://dx.doi.org/10.1680/geot.53.7.619.37383

Xu, D.-S., Borana, L., and Yin, J.-H., 2014, “Measurement of small strain behavior of a local soil by fiber Bragg grating-based local displacement transducers,” Acta Geotech., Vol. 9, No. 6, pp. 935–943, http://dx.doi.org/10.1007/s11440-013-0267-y

Zhang, C.-C., Zhu, H.-H., and Shi, B., 2016, “Role of the interface between distributed fibre optic strain sensor and soil in ground deformation measurement,” Sci. Rep., Vol. 6, p. 36469, http://dx.doi.org/10.1038/srep36469

Zhang, C.-C., Zhu, H.-H., Shi, B., She, J.-K., 2014, “Interfacial characterization of soil-embedded optical fiber for ground deformation measurement,” Smart Mater. Struct., Vol. 23, p. 95022, http://dx.doi.org/10.1088/0964-1726/23/9/095022

Zhu, H.-H., Shi, B., Yan, J.-F., Zhang, J., and Wang, J., 2015, “Investigation of the evolutionary process of a reinforced model slope using a fiber-optic monitoring network,” Eng. Geol., Vol. 186, pp. 34–43, http://dx.doi.org/10.1016/j.enggeo.2014.10.012

Zhu, H.-H., Shi, B., and Zhang, C.-C., 2017, “FBG-based monitoring of geohazards: Current status and trends,” Sensors, Vol. 17, No. 3, p. 452, http://dx.doi.org/10.3390/s17030452