In the depths of China’s coal mines, a silent battle is underway. As mining operations delve deeper into the earth, the stability of surrounding rock becomes increasingly precarious, posing significant challenges and risks. A recent study published by CUI Yi, a researcher at the School of Resources and Safety Engineering, Chongqing University, sheds new light on how to better understand and manage these subterranean stresses.
Cui’s research, published in the Journal of Mining Science and Technology, focuses on the mechanical properties and crack evolution patterns of sandstone with prefabricated double fractures. This might sound like a mouthful, but it’s crucial for anyone involved in deep coal mining. As Cui explains, “The impact of mining disturbances increases with depth, making it more difficult to control the development of surrounding rock fractures.”
The study involved uniaxial compression tests on sandstone samples with prefabricated double fractures. By using Digital Image Correlation (DIC) technology, Cui and his team monitored surface displacements in real-time, providing unprecedented insights into the behavior of sandstone under stress.
One of the key findings is the identification of a ‘sub-instability stage’ in fissured sandstone. Unlike intact rock, fissured sandstone exhibits a stress drop, entering this sub-instability stage after the first stress drop. This stage is critical because it provides a window of opportunity for early warning and intervention.
The length of the rock bridge—the intact rock between the two fractures—plays a significant role in this process. As the rock bridge length increases, the duration of the sub-instability stage decreases, and the stress change during this stage also decreases. Moreover, the rock bridge length affects the propagation of secondary cracks on the surface, leading to local disintegration in secondary cracks.
So, what does this mean for the energy sector? Well, understanding these processes can greatly enhance the monitoring and early warning systems for instability and failure of surrounding rock in coal mines. This could lead to safer mining operations, reduced downtime, and ultimately, more efficient and cost-effective coal extraction.
Cui’s work is a significant step forward in this field. By providing a detailed analysis of the mechanical properties and crack evolution patterns of sandstone, it offers valuable insights that could shape future developments in mining technology. As we continue to push the boundaries of what’s possible in deep coal mining, studies like this will be instrumental in ensuring that we do so safely and sustainably.
The research was published in the Journal of Mining Science and Technology, a publication that translates to English as the Journal of Mining Science and Technology. The findings offer a beacon of hope for the energy sector, illuminating the path towards safer, more efficient mining practices in the depths of the earth.
