Search Results (3)

After water gushing occurs in a coal mine roadway, abundant aggregate needs to be perfused into the water gush roadway to establish a water interception section and reduce the current velocity. Clarifying the water-intercepting aggregate motion path and quantitatively calculating the displacement distance are critical for determining perfusion hole spacing. This paper employs the CFD-DEM coupling approach, which is capable of accurately characterizing the water gush continuous flow properties and the aggregate discrete motion behavior. This can be used to simulate and analyze the water-intercepting aggregate motion in a water gush roadway, categorizing it into three phases: free fall, curvilinear projectile, and sliding. The theoretical motion model aggregate can be developed, and the calculation formulas for aggregate motion distances in each phase derived. A parameter test scheme was designed and combined with numerical simulation methods to verify the accuracy of the formulas. Finally, based on this research, it is proposed that the theoretical model can be used to dynamically optimize the design of perfusion hole spacing, maximizing the synergistic effect of multi-hole perfusion. The selection of aggregate density and size should ensure the vector sum of the aggregate motion distance in phase II and III approaches zero, thereby improving the water-intercepting efficiency. Full article

Mine water disaster is one of the main natural disasters in underground mining operations, and seriously threatens the safety of mine production and personnel’s life, affecting mine safety and sustainable development. The research on the prevention and control of the disaster of water inrush in fractured rock mass has become a major international frontier issue in the field of underground engineering, and it is also a major national demand. The key to effectively preventing and controlling disasters is to reveal the mechanisms of disasters. Taking the Huize lead–zinc mine as an example, this paper deeply studies the application method of the transient electromagnetic method (TEM) in advance water detection in shaft and roadway development and field test results. In view of the complicated hydrogeological conditions of the mine and the serious threat of water damage, this paper puts forward a kind of advanced water detection technology for the Huize lead–zinc mine based on the mine transient electromagnetic method. The technology uses the principle of electromagnetic induction to detect the water-bearing structure ahead by placing the transmitting and receiving coils in the shaft. In the field test, the multi-turn small wire frame device is used to detect the direction of the roof, bedding and floor of the roadway head on. In roadway excavation, if the site meets the detection requirements, the abnormal low-resistance area in the test area can be exposed by drilling first. The degree of structural development and the peak value of water gushing in the target area have been mastered. Then, it is determined whether it is necessary to increase borehole exploration in other relatively high-resistance low-risk areas. The experimental results show that the mine transient electromagnetic method can accurately identify the low-resistance water in front, and provide reliable technical support for mine water disaster prevention. The research in this paper not only enriches the application field of the mine transient electromagnetic method, but also provides a useful reference for mine water damage prevention under similar conditions. Full article

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. Full article