Experimental Study on Overlying Strata Movement Characteristics and Distributed Optical Fiber Characterization of Stope

Abstract

In order to study the migration characteristics and strata behavior law of mining-induced rocks in fully mechanized caving face of coal mine, taking the actual geological mining of Longwanggou Coal Mine as the background, using computer software (KSPB) to identify the location of key strata. The physical similar material simulation test was used to monitor the movement characteristics of mining-induced rocks by using the internal displacement sensor (IDS) and distributed optical fiber sensor (DOFS). A three-dimensional physical model of 3.6 m × 2.0 m × 2.0 m was built; the internal displacement of rock was measured by IDS. BOTDA distributed optical fiber was used to monitor the dynamic movement and deformation law of coated rock. Finally, the two monitoring results were compared and analyzed. The results show that: (1) the displacement curve of the fractured rock mass in the key strata shows a “stepped” increase; (2) based on the analysis of displacement continuous monitoring results, the strata behavior law of working face is obtained. The first weighting interval of 61601 working face is 90 cm, and the periodic weighting steps are 105 cm, 115 cm, 135 cm, 150 cm, 165 cm, 180 cm, 215 cm, and 240 cm; (3) the average strain of fiber is proposed. The first weighting and periodic weighting laws of the working face are represented by the average strain, which are consistent with the experimental phenomena. The first weighting in the average strain curve shows the first mutation peak, and the periodic weighting shows the periodic mutation peak change of the average strain curve.