Internal strain monitoring for coal mining similarity model based on distributed fiber optical sensing

By using PPP-BOTDA, a kind of distributed optical fiber sensing technology, the deformation behavior of a similarity mining model was quantitatively obtained and analyzed based on the strain distribution of the sensing cables. The sensing cables were embedded vertically in the similarity materials during the model construction. When the mining face was gradually approaching and passing through the optical sensing cable, the cable strain shows a process of compression, tension and compression again in general, which can indicate the deformation of surrounding strata in the vertical direction. The peak tensile strain appeared in the soft strata and the interface of soft and hard strata. In comparison with the deformation of photogrammetry, it can be concluded that the distributed optical fiber sensing technology is an effective method for strata strain monitoring in similarity model test of coal mining, especially when the deformation of the model is small. It is feasible to analyze the deformation, such as the height of caved zone and bed separation according to the cable strain distribution and its variation.