Meitan xuebao (Apr 2024)
Deformation zoning characterization of mining rock mass based on partition coupling optical fiber sensing
Abstract
Distributed optical fiber sensing is an important tool for understanding the dynamic evolution of mining rock movement, and the accuracy of monitoring data mainly depends on the fiber-rock coupling relationship. In this study, the 22207 working face of the Buertai Coal Mine in the Shenmu Mining Area was selected as the research object. The distributed optical fiber sensing technology was applied to similarity model tests, combined with the fiber-rock coupling relationship, to explore the inherent connection between the spatiotemporal evolution characteristics of mining-induced overlying strata vertical zoning and the peak strain data locations along the optical fiber. To address the issue of measurement errors caused by the influence of the fiber-rock coupling relationship on the strain data, a new method was proposed to characterize the fiber-rock coupling relationship using the percentage of fissures in the rock mass. Through the experiments on the fiber-rock coupling relationship, a linear function relationship between the fiber-rock strain transmission coefficient and the percentage of fissures in the rock mass was obtained. The binary method was used to process the model images and obtain the variation of fissures in each region. The strain transmission coefficients of the buried optical fiber in the mining-induced overlying strata were calculated in different zones, providing support for further exploring the relationship between the peak strain data and the vertical zoning characteristics of mining-induced overlying strata. The study showed that the peak strain data locations along the optical fiber can be used to characterize the key stratum position below and the zoning of the overlying strata. A model representing the key stratum position below and the zoning of the overlying strata was constructed. By using the peak detection algorithm, the positions of the key stratum were identified as 44, 68, and 107 cm, and the development heights of the falling zone and the water flowing fractured zone were determined to be 35 cm and 68 cm, respectively. The algorithm's identification results were consistent with the theoretically calculated values, and they were in line with the actual situation of the 22207 working face. The research findings have improved the accuracy of distributed optical fiber sensing technology in the field of monitoring dynamic deformation of mining rock, providing new research ideas for characterizing key stratum positions and rock zoning.
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