Distributed Fiber Optic‐Based Monitoring and Analysis of Flexible Molded Concrete Piers for Coal Pillar Free Mining

To address the challenge of monitoring the stress evolution in flexible‐molded concrete pier columns during secondary mining in coal pillarless mining operations, this study aims to develop and validate a real‐time monitoring method based on distributed fiber optic sensing (DFOS) technology. With an engineering background of the Zhaozhuang coal mine as the engineering background of coal pillar mining without coal pillar mining along the hollow stay pillar, on‐site research, laboratory tests, theoretical analysis, and on‐site tests were adopted to study how to accurately, comprehensively, and accurately grasp the stress distribution of soft‐molded concrete pier columns and its evolution characteristics under the influence of secondary quarrying movement in coal pillar mining without coal pillar mining along the hollow stay pillar. The results of the study show that the calibration test determines the characterization formula between the optical fiber phase change and the stress of the flexible concrete pier column. The stress monitored by the optical fiber is highly consistent with the measured stress in the value and trend. Downhole observations were found to be consistent with the fiber‐optic monitoring data, and timely measures were taken, and comparison of fiber‐optic monitoring and traditional stress gauge monitoring results showed consistency.