Researchers have made an important discovery about how the drainage of confined water from coal seam roofs can impact the stress distribution in the coal seam, which is a critical factor in preventing devastating coal mine disasters like coal and gas outbursts and rock bursts. Their findings provide valuable insights for coal mine operators to better predict and control these dangerous events.
Understanding the Impact of Roof Water Drainage on Coal Seam Stress
Coal and gas outbursts, along with rock bursts, are major safety hazards that threaten the operations of coal mines. These dynamic disasters are often triggered by changes in the stress distribution within the coal seam, which can be influenced by various geological conditions. One key factor is the drainage of confined water from the coal seam roof.
When the confined water in the coal seam roof is released, the changes in the lithology and water pressure of the drainage area can lead to movements in the overlying strata, ultimately affecting the distribution of stress in the coal seam. Researchers set out to investigate this phenomenon in detail, using a combination of theoretical analysis, numerical simulations, and on-site monitoring.
Stress Increases Locally After Drainage
The researchers found that after the drainage of confined water, the local stress within the coal seam actually increases, with a stress concentration factor of 1.35. This means that the maximum stress in the stress rising zone can reach up to 23.02 MPa, significantly higher than the baseline stress of 17.10 MPa.
Importantly, the theoretically calculated stress influence range aligned closely with the measured results from a mining case study, validating the accuracy of the researchers’ approach.
The Shape of the Water-Rich Area Matters
The researchers also discovered that the shape of the water-rich abnormal area, specifically the angle of the boundary, has a significant impact on the stress distribution after drainage.
Their numerical simulations showed that as the boundary angle of the water-rich abnormal area expands, the extreme value of the drainage stress increases linearly. The researchers found a strong positive correlation, with an R^2 value exceeding 0.98.
Implications for Preventing Coal Mine Disasters
These findings hold important implications for coal mine operators. By understanding how the drainage of confined water from coal seam roofs can affect the local stress distribution, they can better predict and control the risk of dynamic disasters like coal and gas outbursts and rock bursts.
The researchers’ work provides a valuable framework for analyzing the stress distribution in coal seams, particularly in areas with irregular water-rich conditions. This knowledge can help mine operators implement more effective strategies for disaster prevention and control, ultimately enhancing the safety and sustainability of coal mining operations.
Author credit: This article is based on research by Fenghui Li, Yuming Gu, Yunhai Cheng, Dong Li, Yifan Wang, Shuang Zhang.
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