Researchers at the Gengcun Coal Mine have revealed insights on the movement law of overlying strata and strategies for rockburst prevention during mechanized mining operations targeting extra-thick coal seams.
Rockburst events, abrupt releases of built-up energy within rock formations, present significant hazards for mining operations, especially when working with ultra-thick coal seams. The Gengcun Coal Mine, located in Mianchi County, Henan Province, faces challenges linked to these events as they exploit coal layers with substantial geological pressure.
To investigate these issues, the research team employed theoretical analysis and numerical simulations utilizing the UDEC model, focusing on the movement behavior of the stratum above the mine workings—what they termed the "key layers." Their findings explicitly outline the instability characteristics of these strata and how they influence rockburst risks.
The study established mathematical formulas to measure the instability scale of the overlying hard rock strata, providing precise assessments of stress distributions and movement patterns. Notably, within the research area above mining face 12,240, researchers identified one low-level and three mid-level hard rock strata.
One of their most compelling findings was the behavior of the low-level hard rock layer, which faced periodic instability approximately every eight meters as the mining progressed, indicating heightened rockburst potential. This research is particularly relevant because energy generated during the instability of these rock layers can significantly impact the safety of mining operations.
The scientists stated, "The initial instability release energy of the low-level hard rock layer exceeds the threshold for rockburst occurrence," indicating the necessity for immediate interventions. Such insight is invaluable for optimizing mining operations to improve safety standards.
Implementation of preventive measures is now more urgent than ever as the risk of rockburst can escalate with inadequate monitoring. The researchers recommend maintaining the overburden cutting scale below 10 meters. They assert, "To reduce rockburst risk, maintaining the cutting scale at 10 meters significantly minimizes energy release during instability events," bolstering the framework for safer mining practices.
The simulation data were cross-referenced with on-the-ground measurements, ensuring reliability. Monitoring stations were set up to gather real-time data on pressure and support resistance as the working face advanced. Such detailed monitoring allows for judicious timing of responses to variances detected during operations.
Further, this research highlights collaborative efforts needed to blend theoretical models with practical applications to safeguard mine workers and optimize extraction processes. This dual approach is bolstering operational adjustments within the Gengcun Coal Mine and potentially serves as a model for similar mining operations under comparable geological stresses globally.
Conclusively, the research findings are poised to reshape the methods of rockburst risk management and contribute to developing more secure mining protocols. The goal is to apply these principles widely across the coal-mining sector, reducing the likelihood of rockbursts and enhancing worker safety.
With the global demand for coal continuing, these innovations are becoming increasingly pivotal. The science of mining is not just about extraction—it's increasingly about doing so safely and effectively, minimizing risks inherent to geological conditions.