Advances in Photonics: Experimental Study on Fiber Optic Strain Characterization of Overlying Rock Layer Movement Forms and States

Researchers from Shandong Huayu University of Technology in Dezhou, People's Republic of China, have conducted an experimental study on the fiber optic strain characterization of overlying rock layer movement forms and states using distributed fiber optic sensing (DFOS). The study aimed to investigate the movement laws of hard overlying rock layers, which is crucial for improving coal mine safety production. The researchers conducted an indoor similar simulation experiment based on an actual coal mining face and obtained significant results.

Key Takeaways:

• The strain distribution of horizontally laid optical fibers was characterized by an upward trapezoidal convex platform, reflecting the evolution law of various horizontal movement forms of overlying rock layers.
• The strain curve of vertically laid optical fibers was characterized by two levels of right-handed trapezoidal protrusions above and below, representing the motion state of the upper voussoir beam-lower cantilever beam structure of the overburden.
• The experimental results showed that the range and height of the failure deformation of the overlying rock layers developed in a stepped shape as excavation progressed.
• The final vertical development heights of the cantilever beam structure and the voussoir beam structure in the overburden were 90.27 m and 24.99 m, respectively.
• The experimental results are highly consistent with the UDEC numerical simulation and mandatory calculation formulas, verifying the feasibility of the experiment.
• The research provides theoretical and experimental support for safe coal mining in practical working faces.

Statistics:

• The strain distribution of horizontally laid optical fibers showed an upward trapezoidal convex platform with a range of 10-50 m.
• The strain curve of vertically laid optical fibers showed two levels of right-handed trapezoidal protrusions above and below, representing the motion state of the upper voussoir beam-lower cantilever beam structure of the overburden.
• The range and height of the failure deformation of the overlying rock layers developed in a stepped shape, with a maximum height of 24.99 m.
• The final vertical development heights of the cantilever beam structure and the voussoir beam structure in the overburden were 90.27 m and 24.99 m, respectively.

Sources:

• "Experimental Study on Fiber Optic Strain Characterization of Overlying Rock Layer Movement Forms and States Using DFOS." Photonics, vol. 12, no. 4, 2025, pp. 321, doi: 10.3390/photonics12040321.
• NewsRx. Studies in the Area of Photonics Reported from Shandong Huayu University of Technology (Experimental Study on Fiber Optic Strain Characterization of Overlying Rock Layer Movement Forms and States Using DFOS). Science Letter. May 16, 2025; p 1327.