1. Overview of the work surface The west part of 4196 is at the -740m level and the sixth sub-stage of the fourth mining area. The upper part is the 4195 west goaf, and the lower part is the unmined area. The working face has a length of 839m, a slope length of 142m, a coal seam inclination of 25', and a coal thickness of 2.55m. The direct top is gray siltstone , calcium mud cemented, layered joint development, brittle and brittle and easy to fall; the direct bottom is sandy clay rock, gray to brown, expansive to water, thick 3.6m. The upper channel is the track channel, the lower channel is the transportation channel, all are arranged along the 19-story coal, and the lower part of the transportation channel is provided with the working surface hydrophobic channel, which is specially used for working surface drainage, and the hydrophobic lane is arranged along 19 layers of coal, trapezoidal The section, the transport channel and the hydrophobic lane are connected by 8 communication lanes for hydrophobic standby. The working face adopts the longwall retreat coal mining method, and all the slumping methods manage the roof and comprehensive mechanized coal mining. MG150/375-W type coal mining machine fell coal, coal, SGD630/264W scraper conveyor to transport coal, ZY2800/14/32 shielded bracket support roof. The mining height is 2.55m and the cycle progress is 0.6m. 2. Hydrogeological conditions of the working surface 2.1 Analysis of water inrush from working face The main water-filled aquifer in the working face is the five- or six-ash ash and the ash of the bottom plate. The distance from the 19-story coal is 18.7, 33, 60m respectively. The five or six ash is the direct water-filling source and the indirect water-filling source is the ash. Because the mining area is located in the deep part of the mine, the water supply of the five, six ash and the ash becomes very uneven. The five or six ash mainly uses the structural fissure to give water, and the ash mainly gives water to the ancient karst fissure, which is in the destruction of the strong structural belt. Nearby, there are vertical fissure channels that communicate with each other up and down, so that the main water-bearing rock sections of the ash are connected to each other. Through these fissures, the ash water is replenished with five or six ash. At present, eight working faces have been recovered in the latter four mining areas. Except for the east side of 4194, water inrush occurred in other working faces, and the water inrush was 180-900 m3/h. At the beginning of water inrush, the water volume was generally large and the water level dropped significantly. The maximum water quantity duration is short. From the analysis of the water inrush and water level changes in the whole mine, the ash water in the mine field should be a semi-closed finite replenishment boundary condition, and the dynamic water replenishment is small, so the dynamic water supply to the fourth mining area is entered. It is not sufficient, but because of the large catchment area, the large amount of water storage in the Austrian ash is large, and the maximum water inrush is much larger than the normal water inflow. The water pressure of the hole in the 4196 West main road is 5.2 MPa, which is greater than the critical water pressure 4.2 MPa. Therefore, the surface is in danger of water inrush. According to the analysis of geophysical data, there are three water-rich anomalies on the surface, which are prone to ash water, which has a great impact on the normal production of the mine. 2.2 Water inflow forecast The 4196 working face and the 4195 working face are adjacent working faces, and the hydrogeological conditions are similar under normal conditions. 3. Relationship between pressure distribution and water inrush at the top and bottom of working face It can be seen that the pre-pressure in the process of propelling the working face is concentrated near the coal wall, and the pressure relief zone is present near the top row of the working face. The bottom plate is damaged under the action of the concentrated pressure. The pressure relief zone is under the action of water pressure. When the bottom plate is bulged, the high-pressure floor water is in the condition that the hydraulic passage is unblocked, and the working surface water inrush occurs. This is also the reason why the water inrush on the working surface often occurs near the top row. On the surface of the 4196 surface on November 23, 2004, the water in the working face burst into water. The resistance of the bracket above and below the water inrush was increased faster (see Figure 2), which was 10.5% larger than normal, indicating that the working surface advances faster. When the water inrush is sudden, it is manifested in the resistance of the stent, and the signs of water inrush are not obvious. However, when the stent increases resistance faster, it indicates that the working surface has a periodic pressure or other (eg, water inrush) condition. After the working face bursts into water, after the working surface is advanced by 3 knives, the support pressure drops to the normal pressure value (below 30 MPa). 4. The main measures and effects adopted. (1) Increase the intensity of water exploration and release. According to the low-resistance anomaly zone delineated by the geophysical data, five drilling rigs were constructed in the west main road of 4196, the water discharge of the drilling was 240m3/h, and the water pressure had dropped from the initial 6.2MPa to 5.2MPa. (2) Strictly control the mining height of the working face, and it is strictly forbidden to damage the bottom plate when cutting coal. (3) Strengthen the quality management of work surface support. Make sure that the initial support force of the bracket reaches 24 MPa, ensure that the bottom plate is evenly stressed, and reduce the damage of the bracket pressure to the bottom plate. (4) The working face is pseudo-tilted and the upper part of the working face is 10m ahead of the upper part of the working face, so that the water in the working face can smoothly enter the mined area. (5) After the working face bursts into water, a 250mm diameter drain pipe is laid on the working face, and a water retaining wall is set to direct the water to the draining road to reduce the flushing of the water flow to the working floor. (6) The geological personnel strengthen the observation of the drilling water in the main tunnel of 4196. If the water output suddenly increases, report to the dispatching room in time and find out the reason. (7) The personnel of the mine pressure department are divided into three classes to inspect the change of the bearing resistance of the working face. When the working surface cycle comes to the pressure or the bracket resistance suddenly increases, the work area is notified in time to take preventive measures. (8) Send a special person to clear the 4196 main road, the last four sedimentation tanks, and the last four Shimen ditch at any time to prevent coal from rushing into the water tank and reduce the capacity of the water tank. 5, the conclusion The fully mechanized mining face was harvested from the beginning of October 15, 2004 to the end of May 7, 2005. A total of 2 water inrush from the floor occurred. Due to the timely implementation of various measures, the working face was stopped and moved, and the highest monthly output was produced. It has reached 110,000 tons, and the average yield has reached more than 80,000 tons. It has achieved "high production and high efficiency", and more than 80,000 tons of recovered coal, saving 1 million yuan in moving expenses, and total economic benefits of more than 12 million yuan. About the author: Liu Chengnan, engineer, working in the technical department of Panxi Coal Mine. 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Integrated mechanized mining technology for coal seam in deep pressurized water
Pansy coal miners coal seam 19 layers of coal, the coal seam mining in the long-term threat to floor with high-pressure water, has repeatedly floor face water inrush occurred, Pansy 4196 coal face strong water in Ordovician limestone-rich, The rear mining area with large water pressure overcomes the serious threat of water inrush from the ash by adopting ZY2800/14/32 fully mechanized mining support and adopting various drainage measures to achieve safe mining of 4196 surface.