Monitoring and Characterization of Mining-Induced Overburden Deformation in Physical Modeling With Distributed Optical Fiber Sensing Technology

Facing increasingly large and discontinuous structural evolution under the influence of extensive mining activities, some traditional geophysical technical methods of monitoring overburden deformation have become of restricted use. As an advanced sensing technology, the distributed optical fiber sensor has been introduced into rock deformation monitoring by virtue of its good adaptability and high precision. In this paper, an overburden stratum deformation monitoring experiment was performed within a physical model test to explore the deformation characteristics of mining-induced overburden stratum based on distributed optical fiber sensing. The results indicate that distributed optical fiber monitoring is effective, and the Brillouin frequency shift (BFS) variation distribution reflects every aspect of the space-time and movement laws of the overburden stratum. The comparison of measurements of the distributed optical fiber, fiber Bragg gratings, and dial gauges proved the feasibility and reliability and revealed the ability of optical fiber measurement to monitor large-scale macroscopic deformation, and capture subtle deformation along the entire overburden stratum. More importantly, the BFS variation distribution presents a three-step form, which explicitly identifies the zoning development of overburden stratum. In turn, a conceptual model for describing the overburden deformation process is provided; it illustrates the inversion mechanism of the BFS variation distribution in reaction to the typical overburden deformation structure. This study aims to provide a theoretical and methodological foundation for the application of distributed optical fiber sensing (DOFS) measurement in mining ground control research.