At present, there are 47 coal mines in China with mining depth reaching 1,000 m, of which, the Suncun coal mine of the Xinwen coal mining district in Shandong Province, is the deepest one with a depth of 1,500 m.
Since 2004, the mining depth in Huainan coal mines has reached 700 1000 m, all 15 mines are classified as being outburst-prone, and the coal seams are characterized by low permeability (0.001 mD), high gas content (12 36 m3/t), and high gas pressures (up to 6 MPa).
As early as in 1980, the maximum mining depth of coal mines in Germany, former Soviet Union, Poland, Japan and France, had reached 1,000 m; in 1990s, the most mining depth in Germany was beyond 1,500 m, those of Russia and Poland were 1,400 and 1,300 m, respectively (Hu et al. 2011).
The mining depth of many coal mines in the mid-east region of China has currently reached 800 1200 m, with vertical stress of 22 33 MPa, coal seam gas pressure and content of more than 6 MPa and 20 m3/t, respectively, and coal seam permeability of less than 0.001 mD all of which make gas drainage even more difficult.
87.6 87 aH is the mining depth.
The maximum mining depth was around 900 m.
The increasing mining depth directly causes larger in situ stresses.
The maximum mining depth is around 1,000 m.
As mining depth and intensity increase, mining geology and technical conditions are becoming increasingly complicated.
Ground temperature of geothermal field in deep mines gradually increases with the mining depth.
