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Coal bursts in longwall mines: DAS-based monitoring strategies and numerical modeling insights
Chambers, Derrick James Allen
Chambers, Derrick James Allen
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2024
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2026-04-09
Abstract
In many nations, coal mining plays an important role in energy and steel production and provides economic opportunities for workers. However, coal miners face substantial hazards that result in injuries and fatalities each year. One such hazard is coal bursting: violent, dynamic failures that are difficult to manage and poorly understood.
This work aims to advance the management of coal burst risks in longwall mines by improving monitoring practices and the understanding of coal burst mechanics through applied geophysics and numerical modeling. The first part demonstrates several novel strategies based on distributed acoustic sensing (DAS) — a technology that uses laser pulses to measure dynamic strain in fiber optic cables — for monitoring seismicity in underground longwall coal mines. DAS cables deployed along the mine floor and in boreholes constitute a general monitoring strategy to overcome many challenges inherent in traditional (non-DAS) monitoring. Other DAS deployment approaches, such as seismoacoustic arrays near the mining face, show promise for addressing specific ground control challenges. A new open-source framework is also presented that facilitates DAS research by simplifying data processing and management.
The second part of this work focuses on understanding coal burst mechanics, particularly for coal bursts occurring near the longwall mining face. Quasi-dynamic numerical modeling is used to quantify the effects of several parameters on coal burst severity. The length of the cantilever and the strength of the coal-rock interface play the most critical roles. Similar models are used to examine the contributions of various components to the coal burst seismic wavefield. In most cases, excavation deformation dominates other source component contributions. In practice, this means far-field seismic recordings are of limited value for directly studying coal burst damage but may be useful for determining cantilever length and burst depth. Moreover, moment tensors should be used cautiously when interpreting failure mechanisms since distinct sources can produce similar moment tensors. The modeling results and geophysical data suggest that the coal bursts studied in this work initiate near the mining face and are caused by cantilever loading, elastic energy stored in the coal, and a strong coal-rock interface.
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