Gas emission control of tunneling in geological st

2022-08-09
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Gas emission control in geological structure area

1 overview

with the increase of mining depth, the gas in coal mine is also increasing. Among them, the relatively large changes are mainly concentrated in the geological structural belt

well 9 of Didao mine is a high gas well, with an absolute gas emission of 10.98m3/min and a relative emission of 20.95 m3/T. Mining is divided into East and west mining areas after 2002. The east mining area has been mined since 1960, mainly mining 20, 19, 18, 17 and 12 coal layers. Until 1999, it was mined to the level of No. 11 road. During the development preparation process, no gas emission was found in the geological structure belt. After 2000, the development preparation was below the level of left No.12 road. In the process of development preparation and excavation, the gas emission was relatively large when encountering small geological structural zones. The most obvious change was the excavation and transportation of the 20 storey main roadway of left No.12 road in March 2003. When the main roadway was excavated and transported 150m, it encountered a small one. If the gate froze, the influence of injection pressure and pressure holding pressure would disappear. With the increase of mold temperature, the cooling and finalization time would also be extended, Therefore, after demoulding, the shrinkage rate of the products will generally increase. The normal fault has a drop of 4m and an inclination of 40 °. When the fault is exposed, gas ejection occurs at the roof fault, accompanied by sound. At that time, 11kw fan was used for air supply in the main roadway. The air supply volume of the fan was more than 300 m3/min, the end air volume was 100 m3/min, and the return air volume of the main roadway was 120 m3. The sensors were divided into imported and domestic/min. The gas concentration of return air in normal excavation is 0.4%, and the absolute emission is 0.48 m3/min. in case of fault eruption, the gas concentration of return air is 1.5%, and the absolute emission is 18 m3/min. According to past experience, the gas concentration will gradually decrease after a few days of spraying. Half a month after the shutdown, the gas concentration did not drop. At that time, the 130 coal mining team was mining on the 18th floor of the left 13 road. In order to ensure the safety production of the 130 coal mining team, the main roadway was closed in time

the 20 layer of the left 13 road is the upper layer of the level of Jiujing 13 Road, with a mining height of 2.0m. The mining is mainly to liberate the gas of 12 ~ 19 layers. The reasons for the increase of gas change this time: ① the 20 layer is the deep layer that has not been mined. ② The gas gradient in deep mining increases. ③ The upper part of the 20th floor is 21 ~ 23 floors, with a distance of 10 ~ 30m. ④ The geological structure zone is a normal fault, (open fault) which is easy to communicate with other layers and stores a large amount of gas in the fracture

see Figure 1 for the ventilation system of 10 ~ 13 roads on the left of East mining

Figure 1 Schematic diagram of the ventilation system of the left 10 ~ 13 roads in the east mining

2 preventive measures

(1) the outer part of the 20th floor of the left 13 road is broken and closed, and the inner part is 140m away from the main lane, which is re closed

(2) send the return air on the 20th floor up the mountain at 130m of the main roadway

(3) drill at 135m of the main roadway (see Figure 2), and the front fault must be penetrated when drilling

Figure 2 drilling layout on the 20th floor of the left 13 Road

(4) drilling must also be completed after going up the hill and sending it through; Adjust the whole ventilation system of Road 10 ~ 13 on the left of East mining (see Figure 3)

(5) adjust the route: left No. 13 Road, 20th floor → 20th floor uphill → left No. 12 road, 19th floor main lane → return air inclined upward → left according to the "energy saving and new energy vehicle technology roadmap" previously released by the Chinese society of automotive engineering, 11 road

20th floor alley → general platoon

Figure 3 Schematic diagram after the adjustment of the ventilation system of the left 10 ~ 13 roads in the east mining

extraction and drainage system: drilling → extraction and drainage pipeline → stone gate on the 18th floor of the left 13 Road (the stone gate is installed and sealed) → inner stone gate on the 18th floor of the left 13 Road → empty area on the 18th floor of the left 13 Road → air duct on the left 11 road

(5) the inner part was broken and sealed to discharge gas, and the fault of the working face was ventilated with local ventilator under positive pressure to deal with the gas emission from the fault

(6) expand the excavation and delivery section of more than 7 m2, increase the air supply volume of the roadway, and reduce the gas concentration in the return air of the main roadway

(7) when the conditions are met, install and discharge pumps as in the current situation 1 to discharge fault gas

through the above treatment, now the working face has passed through the fault area, the return air gas of the main roadway is 0.5%, and the absolute emission is 0.5 m3/min, ensuring the normal and safe excavation of the 20th floor of the left 13 road

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