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Experimental study on distributed optical fiber sensing monitoring for ground surface deformation in extra-thick coal seam mining under ultra-thick conglomerate
摘要： The purpose of this paper is to study the law of ground surface movement and deformation in deep and extra-thick coal seam mining under ultra-thick conglomerate. With the engineering geological conditions of Qianqiu Coal Mine as the background, the three-dimensional model with the size of 3600 mm × 2000 mm × 2000 mm (length × width × height) was constructed. The distributed optical ?ber sensing monitoring network is set up in the model. The optical ?ber sensing signal is collected in real time by NBX-6055 demodulator to characterize the surface movement and deformation. Then based on the Mohr-Coulomb criterion, the numerical calculation model is established by using UDEC 6.0 software to explore the internal relationship between overburden and surface movement and deformation in the process of coal mining. The test results show that the distributed optical ?ber monitoring technology can e?ectively capture the movement and deformation of ground surface. The optical ?ber strain distribution curve can accurately locate the formation area and stress state of surface subsidence basin. The surface is controlled by the key strata of ultra-thick conglomerate, and in the whole process of mining, the surface movement and deformation can be roughly divided into three stages: deformation initiation, slow deformation and sudden deformation. The conclusions indicate that the distributed optical ?ber sensing monitoring technology has good applicability in the surface monitoring of model test. It provides a method for the monitoring information research of mining surface movement and deformation.
关键词： Three-dimensional model,Surface movement and deformation,Ultra-thick conglomerate,Numerical calculation,Distributed optical ?ber sensing technology
更新于2025-09-16 10:30:52
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Selection of spectrum model in estimation of Brillouin frequency shift for distributed optical fiber sensor
摘要： To improve real-time performance in distributed optical ?ber sensor, the in?uence of Brillouin spectrum models on performance in estimation of Brillouin frequency shift (BFS) is systematically investigated. First, the related Brillouin spectrum models, objective functions, optimization algorithms and convergence criterion in estimation of BFS are introduced. The BFS estimation algorithms based on the Lorentzian, Gaussian, pseudo-Voigt and Voigt models are written in MATLAB. The algorithms are used to estimate BFS for numerically generated Brillouin spectra with di?erent values of SNR (Signal to Noise Ratio) and measured Brillouin spectra with di?erent values of pulse width and average time. The results reveal that regardless of the simpli?ed Lorentzian and Gaussian models or more accurate pseudo-Voigt and Voigt model-based algorithms used, the estimated BFS between di?erent algorithms is quite similar. However, the ?tting error of the simpli?ed model-based algorithms is larger than that of the more accurate model-based algorithms especially for the cases with high value of SNR. The computational burden of the former is less than that of the latter. The Voigt model-based algorithm requires the most computational e?ort. If the nonlinear least-square ?t method is used, the selection of spectrum model has no big in?uence on the accuracy in the estimated BFS. Therefore, the algorithm based on simpli?ed Lorentzian and Gaussian models should be selected in BFS estimation. Thus, not only high accuracy in BFS estimation is ensured, but also the computation time can, at best, decrease to one-tenth of the maximum value.
关键词： Spectrum model,Accuracy,Computation time,Brillouin frequency shift,Distributed optical ?ber sensing
更新于2025-09-12 10:27:22