Local Calibration of Fiber-Optic Sensing for Detection of Deformation Signs in Rockburst Hazard Prediction
A. I. Konurin, D. V. Orlov
Chinakal Institute of Mining, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: Rock bursts, rockburst hazard, geomechanical monitoring, deformation monitoring, fiber-optical testing, Optical Time Domain Reflectometer, OTDR, FDOS, deformation signs, intelligent data analysis, multimodal prediction
Abstract
The authors propose a methodical approach to formation of deformation-sensible indicators from the local control of fiber-optic sensing for the further utilization in integrated rockburst hazard prediction systems. The research uses the advanced instrument of Dual-Wavelength Optical Time Domain Reflectometer (OTDR) applied to a single-mode fiber-optic sensing cable with a local sensible stretch generated as a controllable optical heterogeneity. The operation of OTDR is described, as well as its difference from the Distributed Fiber-Optic Systems and the range of the methodically correct application of the local OTDR-based approach are discussed. Discriminability of the indicators in transition between the sensing mode, reproducibility of signal in re-fitting of the sensible stretch and probability of detection of a local heterogeneity from a series of repeated OTDR measurements is assessed. It is shown that the most informative indicators are the amplitude factors at the wavelengths of 1310 and 1550 nm, as well as their difference and increment relative to the reference condition. The criteria of withdrawal of fitting-dependent and unstable parameters from the space of indicators used for the further joint analysis with the data of microseismicity are formulated.
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