Damage Characteristics and Mechanism of the 2017 Groundwater Inrush Accident That Occurred at Dongyu Coalmine in Taiyuan, Shanxi, China

Abstract

On 22 May 2017, a groundwater inrush accident occurred in the gob area of coal floor at Dongyu Coal Mine in Qingxu County, Shanxi Province, China. The water inrush accident caused great damage, among which six people died and the direct economic loss was about CNY 5.05 million. An elliptical permeable passage appeared at the floor of the water inrush point, and the lithology of the outburst is mainly fragmented sandy mudstone and siltstone of coal roof No.2 in the lower layer of coal seam No.3, which is currently being mined, with a peak inflow of 500 m3/h. The water inrush happened due to following reasons: There is an abandoned stagnant water-closed roadway in coal seam No.2, which is the lower mine group of coal seam No.3. The abandoned roadway of coal seam No.2 is an inclined roadway. The water level of the roadway far away from the accident point is higher than the floor elevation of coal seam No.3. Under the joint action of water pressure, mining disturbance, and weakening of goaf water immersion, the original equilibrium state was broken, resulting in the destruction of the only 7 m water-barrier rock pillar between coal seam No.3 and coal seam No.2. The water in the goaf led upward along the roof crack, gradually evolved from seepage to gushing water, and a large amount of goaf water poured into the roadway in the working face of the 03304 panel, finally leading to the occurrence of catastrophic water inrush. Technically, the miners did not implement the technical provisions of the coal mine water control regulations, leading to the accident. In addition, the failure to arrange evacuees to a safe location after apparent signs of water inrush also increased the catastrophic level of the accident.

Influence Research for Softening and Swelling of Weakly Cemented Soft Rock on the Stability of Surrounding Rock in Roadway

“…Weakly cemented soft rock, such as carbonaceous mudstone, mudstone, and silty mudstone, is distributed widely in the top and floor of coal seams in central and western China under the influence of geological tectonics [1][2][3][4]. Because the low strength, loose cementation, and poor performance of this rock, especially water, will result in softening and expansion, it is always sustainable growth and serious deformation of surrounding rock when tunneling in weak cemented soft rock roadway, drenched by water, leading to some accidents, including the floor heave, roof caving, and collapse, which seriously restrains efficient coal mine production safety [5][6][7][8][9].…”

Mechanism of Changes in Goaf Water Hydrogeochemistry: A Case Study of the Menkeqing Coal Mine

“…Stopping drainage inevitably leads to a rise in the underground water level of the mine and forming goaf water [6,7]. Studies have shown that goaf water not only becomes a potential water hazard when the mine is in operation [8], but also becomes a contamination source of regional groundwater after the mine is closed [9,10]. Due to the influence of mining activities, the underground mining area becomes a gathering place for groundwater in the mining area, and also is a place where physical, chemical, and biological pollution of groundwater occurs [11,12].…”

Identification of Mine Water Source Based on AHP-Entropy and Set Pair Analysis

“…The mine water inrush is ferocious, often engulfing the roadway in an instant and resulting in considerable casualties and economic losses. A total amount of 779 water disasters happened in China, which resulted in enormous casualties (3,831 deaths) and economic losses in the period 2000-2020 [2]. After a water inrush disaster occurs in mine production processing, it is urgent to identify the source of water inrush and formulate the corresponding control measures, and varied control measures should be made out for the different aquifer conditions based on water richness.…”