Application of coal pillarless mining technology for broken roof and pressure relief roadway in Yulan Coal Mine
In recent years, with the increase of coal mining depth, large-scale investment in intelligent devices, pressure mine gas emission and increasing roadway section [1-2]. As the main production mine of Xishan Coal and Electricity (Group) Co., Ltd., the coal seam of Xishan Coal and Electricity (Group) Co., Ltd. has the deepest burial, the highest gas content and the relatively heavy production task, it is under great pressure in roof support, gas control, mining connection and balance. . In order to ensure the safe production of the mine, the 12408 fully mechanized mining face with the most obvious mine pressure, high gas content, relatively loose connection and less prominent risk is taken as an example to study the technology of retaining roadway along the top of the roof. And application.
1 work surface overview
1.1 Working face mining conditions
The 12408 working face of Gaolan Coal Mine is located in the Nansipan District, mining 2# and 3# coal seams at +750m. The working surface is 810-870m high, and the ground elevation is 1029~1175m, that is, the working surface is buried at 210~305m. The 12408 fully mechanized mining face has a length of 240m, the length of the cut-off line is 695m, the coal thickness is 3.85m, the average mining height is 4.2m, and the coal recovery is 765,000t. According to the mining pressure data of other working faces in the same coal seam, the initial pressure step is 29~31m, the cycle step is 12~15m, and the maximum pressure is 58MPa. The working face adopts U-shaped ventilation mode, and the air flow route is belt groove→cutting eye→tracking groove→gas control lane→low-level drainage lane. The track-groove, gas-treated roadway and low-level drainage roadway are arranged on the lower side of the working face. The distance between the track-slot and the gas-treated roadway is 25m, and the low-level drainage roadway is arranged along the 4# coal seam. The distance from the 2# coal seam is 10~. 15m.
The purpose of cutting the roadway in this study is to try to retain the space behind the track along the roadway as a ventilation section after the working face is recovered, so as to realize Y-type ventilation on the working face, that is, a part of the wind flow is behind the upper corner. The movement of the lanes can solve the problem of gas overrun in the upper corner [3]. The test section of the roadway is the area with a length of 200m in the front of the cut line (Fig. 1). The method of retaining the roadway is deep hole blasting top pressure relief + single guarding lane support + anchor cable reinforcement support roof.
1.2 Working face surrounding rock conditions
The dummy roof of the 12408 working face and the direct top thickness are about 3m, and then the top is about 10m thick. In order to realize the roadway, the conditions to be met are as follows: (1) The cutting and pressure relief of the overburden layer on the working face shall be carried out to improve the surrounding rock stress environment of the roadway; 2 to ensure the integrity and regularity of the roof of the roadway, the direct roof shall be neatly arranged. Cut the top. This research adopts the deep hole blasting method, supplemented by single guards and anchor cables to reinforce the roof to realize the roadway along the air.
The surrounding rock conditions of the working face are shown in Table 1.
2Unloaded pressure relief roadway without coal pillar mining technology
2.1 Determination of the height of the broken roof and the distance between the top and bottom of the pressure relief hole
2.1.1 Determination of the height of the top
The numerical model was established according to the coal seam histogram of 12408 working face, and the improvement of surrounding rock stress when the cutting height was 6~25m was simulated. Through analysis, it is found that when the working face is only cut to 14m, the surrounding rock stress environment improvement effect of the track is the best. At this time, the broken roof height also cuts the 10.13m thick siltstone roof. by
It can be seen that the height of the top-pressure relief of the track along the trough is 14m.
2.1.2 Determination of the distance between the top and bottom of the pressure relief hole
In this study, the emulsion of 3# coal mine was used for blasting. The density of explosive was 1120kg/m3 and the detonation velocity was 3600m/s. According to the rock performance parameters, the radius of the crushing ring and the crack ring formed in the roof sand rock were calculated. It is 0.3, 1.2m. In this study, when the diameter of the medicine roll is 63mm and the diameter of the blasthole is 80mm, the radius of the fracture area around the blasthole is about 1.05m after detonation under the surrounding rock conditions of the Shulan Coal Mine. 2m.
2.2 method of top pressure relief
Referring to relevant practical experience, the explosive is taken by the cylinder diameter of 63mm, the diameter of the blasthole is 80mm, and the non-coupling coefficient is 1.26. According to the roof structure of the coal seam of 12408 working face, the top hole is unloaded according to the parameters shown in Fig. 2 and Fig. 3. In order to facilitate drilling and charging, the blasthole must be at an angle of 11° to the vertical direction, that is, an elevation angle of 79°. The blasthole is arranged in a single row, between the holes
Designed by 2m. The blasthole opening is 450mm from the center of the roadway to avoid the anchor tray. The depth of the blasthole is 15m, the length of the charge is 7m, and the length of the seal is 8m. After the rock formation is weakened into a gap along the roadway, it can be broken under the action of mine pressure.
2.3 Chengxiang cutting method
The main purpose of the slitting in Chengxiang is to make the roof of the roadway complete, avoiding the over-excavation and unevenness of the roadway roof, and the main treatment rock formation is the direct roof. The direct top thickness of the track groove is about 3.33m. The depth of the slotted blasthole is 4.5m, the charge is 2m and the mud is 2m. The diameter of the explosives is 35mm, the diameter of the blasthole is 45mm, the elevation angle is 79°, and the pressure relief holes are arranged in a straight line. The arrangement of the blastholes in the roof of the roadway is shown in Figure 4.
2.4 roadway reinforcement method
2.4.1 Anchor cable reinforcement
In order to ensure the stability of the inverted step rock formation above the roadway, it is necessary to make an anchor cable on the roof of the roadway (Fig. 5). The reinforcement anchor cable needs to be constructed before the blasting (can be drilled at the same time as the blasthole). In order to ensure the stability of the roadway during the cutting process and the cycle, the anchorage is used to reinforce the roadway before the top pressure relief and the top cutting, that is, the reinforcement cable is used at the top of the roadway with the centerline 200mm away from the center line. For reinforcement, the anchor cable spacing is 1000mm (Figure 6). The anchor cable specification is 17.8mm×6300mm, the anchor cable tray specification is 200mm×200mm×16mm (length×width×height) iron gasket (medium hole 18～20mm), and the lock adopts OVM15-1 type single hole lock. The anchor hole is 6100mm deep, the anchor cable is anchored by two resin anchoring agents, one roll of MSCK2380 anchoring agent is on top, one roll of MSK2380 type anchoring agent is under, and the pre-tightening force is not less than 120kN.
2.4.2 Monolithic pillar reinforcement
According to the influence range of the leading bearing pressure of the 12408 working face, the front working face 50m is equipped with two rows of DZ45-200/110 single-pillars with a column spacing of 1000mm. In the range of 0 to 40 m behind the working surface, the single-piece support is strengthened, and 3 rows of DZ45-200/110 single-pillar pillars are arranged in the 40m area behind the working surface, and 1 row of dense monomers are arranged near the top line. The column spacing is 600mm, and the arrangement of one beam and two columns is adopted. Within the range of 40 to 70 m behind the working face, a row of dense cells in the roadway can be withdrawn, leaving only two rows of monomers. After 70 m,
The stability of the roadway can be withdrawn all the single columns (Figure 7).
3 conclusions
(1) After the 12408 working face is recovered, the roadway behind the track is successfully completed, and the Y-shaped ventilation of the working face is realized, that is, a part of the wind flow moves along the roadway behind the upper corner, which helps to solve the upper corner gas super Limit the problem.
(2) Through the top-loading pressure relief, the stress distribution in the goaf is optimized, and the deformation of the adjacent roadway is greatly reduced, which greatly reduces the whole roadway project.
(3) By cutting and forming the roadway and reinforcing the support, the roadway behind the goaf of the working face can be reused after the whole lane and sprayed, which greatly reduces the excavation project and reduces the cost per ton of coal.
references
[1] Bai Jianwei, Hou Chaoyu. Research on principle and application of surrounding rock control in deep roadway [J]. Journal of China University of Mining and Technology, 2006, 35(2): 145-148.
[2] Kang Hong Pu, Wang Jinhua, Lin Jian. High prestressed strong support system and its application in deep roadway [J]. Journal of Coal, 2007, 32(12): 1233-1238.
[3] Zhang Lei, Zhao Wei. Exploration and suggestion of deep roadway support technology [J]. Coal Mine Support, 2007, 15 (3): 48-49.
Article source: "Modern Mining", 2017.3
Author: Caojun Wen; Xishan Coal and Electricity (Group) Company Copyright:
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