Research progress of DFOS in safety mining monitoring of mines

In recent decades, many mining researchers have carried out many investigations on"how to accurately and efficiently ensure the safe mining of mines”. Through empirical observation, theoretical calculation, numerical simulation, and experimental study, a number of important achievements have been made in new methods, new technologies, and new applications of safe mining monitoring, which have promoted the continuous progress of safe mining monitoring technology and the continuous improvement of monitoring theory. Distributed fiber optic sensing technology has become the research focus in the field of mine monitoring and application because of its advantages of full distribution, high precision, real-time, large range, and anti-interference. Based on the objective problems faced by coal mining in China, the research methods of mining-induced overburden deformation and failure were systematically reviewed in this paper, which is the core problem of safe mining in mines. Also, the characteristics of several typical DFOS technologies (FBG, UWFBG, OTDR, BOTDR, BOTDA, BOFDA, DAS)and their application scenarios in mine engineering from the aspects of technical principle, sensor selection and system layout were introduced. Combined with the requirements of safe mining monitoring, the comparative analysis of fiber optic sensor selection, instrument selection and monitoring system design, the application progress of DFOS technology in the current key directions of mining engineeringwas summarized, such as mining overburden deformation and damage, mining fault activation, coal pillar stability, bearing pressure, grouting effect evaluation of fracture zone, shaft deformation, goaf ground subsidence, aquifer pressure, curtain wall deformation, open pit slope and fiber optic micro-vibration, mine temperature monitoring and hidden fire detection. The theoretical and technical difficulties in various application directions and the development trend of safe mining monitoring technology were also explored. The problems faced by DFOS technology, such as overburden deformation and fiber optic cable data mutual feed, sensing fiber optic and rock soil coupling performance, artificial intelligence algorithm of massive fiber optic sensing data, fiber optic monitoring characterization method of overburden deformation and damage, the applicability of fiber optic for large deformation monitoring in mines, the construction method of multi-source and multi-field monitoring system, the standardization of technical application, were discussed. Combined with the response characteristics of monitoring data, the coupling performance of rock and soil mass of fiber optic cable, the artificial intelligence algorithm and characterization method of fiber optic data, intelligent whole process monitoring, multi-source and multi-field monitoring and other applications, the corresponding countermeasures were put forward. © 2022 China Coal Society. All rights reserved.