Madjdabadi, B, Valley, B, Dusseault, MB & Kaiser, PK 2014, 'Numerical study of grout–rock mass interaction effect on distributed optical fibre sensor measurements', in M Hudyma & Y Potvin (eds), Deep Mining 2014: Proceedings of the Seventh International Conference on Deep and High Stress Mining
, Australian Centre for Geomechanics, Perth, pp. 457-468, https://doi.org/10.36487/ACG_rep/1410_31_Madjdabadi
Distributed Brillouin sensing (DBS), used initially in structural health monitoring for bridges and pipelines, is attracting attention in the field of strain measurement in underground infrastructure, including mining. Strain measurements along an effectively unlimited lengthoffer opportunities to capture the deformation field induced by underground excavations beyond the excavation damaged zone (EDZ). The potential benefit of such mine-wide monitoring of the deformation field includes improved calibration of stress–strain deformation models.
For underground mines a challenge for rock masses resides in borehole installations that can respond to mining. This response is partly as continuum deformation in extension, compression or shear, or as discontinuum deformation through localised shear or dilation of discontinuities.
The objective of this paper is the optimisation of the installation scheme to ensure proper strain transfer to the measuring fibre while being able to accommodate and measure localised strains induced by discontinuities. To this end, a numerical study was conducted to evaluate the grout and grout–rock interface properties’ effects on the strain transfer process from rock mass to the cable. The grout stiffness was found to be the most influential parameter. Also, slippage along the rock–grout interface is not an issue for the strain transfer process since a deep environment provides a high confining stress on the borehole wall resulting in high shear strength at the interface.
Adachi, S 2008, ‘Distributed optical fiber sensors and their applications’, SICE Annual Conference 2008, IEEE, pp. 329-333.
Bayoumi, A 2010, ‘On the Evaluation of Settlement Measurements Using Borehole Extensometers’, Geotechnical and Geological Engineering, vol. 29, no. 1, pp. 75-90.
Dunnicliff, J 1993, Geotechnical Instrumentation for Monitoring Field Performance, John Wiley & Sons, Inc., New York.
He, J, Zhou, Z, & Jinping, O 2012, ‘Optic fiber sensor-based smart bridge cable with functionality of self-sensing’, Mechanical Systems and Signal Processing, vol. 35, no. 1-2, pp. 84-94.
Inaudi, D & Glisic, B 2006a ‘Distributed fiber optic strain and temperature sensing for structural health monitoring’, in PJ da Sousa Cruz, DM Frangopol, LC Canhoto Neves (eds), The 3rd International Conference on Bridge Maintenance, Safety and Management, CRC Press, London.
Inaudi, D & Glisic, B 2006b ‘Integration of distributed strain and temperature sensors in composite coiled tubing’, in D Inaudi, W Ecke, B Culshaw, K J Peters, & E Udd (eds), SPIE Proceedings Vol. 6167, Smart Structures and Materials 2006: Smart Sensor Monitoring Systems and Applications, SPIE, Bellingham, pp. 1-10.
Iten, M 2011, Novel Applications of Distributed Fiber-optic Sensing in Geotechnical Engineering, PhD thesis, ETH Zurich, Zurich.
Johansson, S & Watley, D 2004, Dam safety: experiences from distributed strain measurements in five embankment dams, ELFORSK Stockholm.
Madjdabadi, BM, Valley, B, Siczkar, L, Dusseault, MB & Kaiser, PK 2013, ‘Laboratory-scale strain and temperature response of a distributed optical fiber sensor’, Proceedings of the 47th US Rock Mechanics/Geomechanics Symposium, American Rock Mechanics Association, Alexandria, paper 13-347.
Mikkelsen, P 2002, ‘Cement-bentonite grout backfill for borehole instruments’, Geotechnical Instrumentation News, vol. 4,
Mohamad, H, Bennett, PJ, Soga, K, Mair, R, Lim, C-S, Knight-Hassell, CK, & Ow, CN 2007, ‘Monitoring tunnel deformation induced by close-proximity bored tunneling using distributed optical fiber strain measurements’, Proceedings of the 7th International Symposium on Field Measurements in Geomechanics, American Society of Civil Engineers, Reston, pp. 1-13.
Naruse, H, Uehara, H, Deguchi, T, Fujihashi, K, Onishi, M, Espinoza, R, Guzman, C, Pardo, C, Ortega, C & Pinto, M 2007, ‘Application of a distributed fibre optic strain sensing system to monitoring changes in the state of an underground mine’, Measurement Science and Technology, vol. 18, no. 10, pp. 3202-3210.
Omnisens 2010, User Manual for DITEST STA-R Fiber Optic Distributed Temperature and Strain Analyzer, Omnisens SA, Morges.
Thévenaz, L 2010 ‘Brillouin distributed time-domain sensing in optical fibers: state of the art and perspectives’, Frontiers of Optoelectronics in China, vol. 3, no. 1, pp. 13-21.