Model test study on overburden settlement law in coal seam backfill mining based on fiber Bragg grating technology

Taking section 3600 of Pingzhuangxi coal mine as the prototype, we made the test model based on the theory of similarity, used the fiber Bragg grating (FBG) to study the deformation characteristics of overburden in the process of coal seam backfill mining and analyze the correlation between filling material and overburden settlement, and obtained the deformation law of overburden in the seam filling area and the coal pillar area. The results show that due to the impact of compression characteristics of filling materials, the intermediate roof, and the breakage of key strata, the overburden deformation in the seam filling area can be divided into 4 stages, and the coal pillar overburden deformation can be divided into 3 stages according to the slope of strain distribution curve of overburden during backfill mining. Based on the slope of the strain curve of mining overburden and the strain value measured by FBG sensors, this paper identified the stability of rock stratum, proposed a FBG-based method to determine the height of the water-flowing fractured zone, compared it with the existing calculation methods to verify its rationality, and came to a conclusion that this new method can be promoted for future calculation.