How Seismic Events Trigger Roof Collapses in Deep Coal Mines

By Muhammad OsamaReviewed by Laura ThomsonSep 3 2025

Researchers have investigated roof collapses in retained top coal roadways caused by high-energy seismic events (HESEs) in deep coal mines. A recent study conducted in the Binchang mining area, Shaanxi Province, China, and published in the journal Scientific Reports explored the mechanisms behind these collapses and their relation to geological conditions and mining practices.

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The findings provide critical insights into roadway stability and propose advanced support strategies to reduce the risk of seismic-induced collapses. It also offers valuable guidance for improving safety and operational efficiency in coal mining operations.

Challenges of Fully Mechanized Top-Coal Caving

Fully mechanized top-coal caving (LTCC) is a widely used technique for efficiently extracting thick coal seams. However, it often leaves a layer of retained coal above the roadway, compromising roof stability. This risk is mainly high in areas experiencing elevated static stress or dynamic loads from HESEs. Therefore, understanding the mechanisms behind these failures is key to improving mining safety and developing effective support strategies.

Analyzing Roof Collapse Dynamics

In this study, the researchers focused on the 301 working face in the Binchang mining area, where a roof collapse was triggered by a HESE releasing approximately 4.67 × 10⁵ J. The coal seam lies between 800 and 1000 meters deep, with an average thickness of 12 meters. They combined theoretical modeling and numerical simulations using the particle flow code in two dimensions (PFC2D), geological assessments, in situ stress measurements, and microseismic monitoring to analyze roadway stability under dynamic loading. Microseismic data were further used to link seismic activity with structural failures, providing insights into the mechanisms of driving roof instability in retained top-coal roadways.

Key Findings on Seismic-Induced Roof Failures

The outcomes showed that roof collapses induced by HESEs exhibit distinct dynamic failure characteristics, differentiating them from typical roof failures. A critical observation was that high in situ stress combined with intense dynamic loading leads to a sudden release of elastic energy, causing catastrophic collapses when anchorage systems are insufficient. Numerical simulations indicated that the likelihood of collapse increased significantly when the lateral pressure coefficient exceeded 1.25 or the HESE intensity surpassed 60 MPa.

A documented HESE on September 29, 2021, released approximately 4.67 × 10⁵ J, resulting in a roadway collapse 320 meters ahead of the working face, with damage extending over 55 meters. Cracks initiated at the interface between the anchorage structure and surrounding rock, rapidly progressing under dynamic disturbances. Events occurring within 17 meters of the roadway were particularly damaging, compromising stability.

The study highlighted the inadequacy of conventional bolt-and-cable systems under dynamic loads. In contrast, extended anchor cables reduced the kinetic energy of the surrounding rock by about 57.41%, demonstrating effectiveness in maintaining stability. These results emphasize the importance of optimizing support systems to mitigate seismic-induced collapses.

Recommendations for Mining Engineering Practices

This research has significant implications for mining engineering practices, particularly in regions prone to HESEs. It underscores the need for advanced roof support systems that withstand static and dynamic loads. The study recommends strategies such as extended anchor cables, optimized support designs, pressure relief techniques, and controlled blasting to enhance roadway stability and reduce the risk of roof collapses.

Furthermore, monitoring in situ stress conditions, seismic activity, and roadway stability is crucial. Integrating real-time monitoring systems could provide early warnings, enabling timely interventions to protect personnel and equipment. Expanding research across different mining environments could lead to more broadly applicable control strategies. Mining operations can improve safety and operational efficiency by combining advanced support systems, proactive stress-relief measures, and robust monitoring.

Conclusion and Future Directions in Mining Safety

This study provides critical insights into roof collapses in coal mining, particularly those induced by HESEs. It explains the mechanisms of roof failure and highlights the need for novel support designs and advanced monitoring technologies. The findings offer practical recommendations for improving support systems and ensuring safer mining operations.

Future work should explore the degradation behavior of support systems, establish instability criteria for anchorage structures under dynamic loading, and further investigate roof stability under varying operational conditions. These efforts will be crucial for developing more resilient engineering practices and adapting to the evolving challenges of deep coal mining.

Overall, this research enhances the understanding of mining-induced seismicity and paves the way for future advancements in mining safety and technology. By adopting innovative solutions and integrating advanced methodologies, the mining industry can improve safety standards and ensure the sustainability of coal mining practices in complex environments.

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