As the development area of ​​Zhaogu No. 2 Mine extends to the west, in order to meet the needs of post-ventilation, it is necessary to set up a return air shaft and its industrial site in the west wing of the mine. In order to ensure that the wellbore is safe, reliable and easy to maintain during construction and use, the rock formation and topsoil through which the wellbore passes should have good hydrological and geological conditions, and do not pass through or less through the flowing sand layer, avoiding larger aquifers. Thicker alluvium, coal seams with dangerous coal and gas outburst, large faults, structural fracture zones, water leakage zones, karst caves, goafs, etc. In order to reduce the production and technical difficulties during the construction of the wellbore, the wellbore should be placed as far as possible in the area with high exploration level [1]. According to statistics, since 2004, about 50% of new mines in China have adopted vertical shaft development methods [2-4]. Due to the large buried depth of the coal seam in Zhaogu No. 2 Mine and the large thickness of the alluvium, the alluvial layer, geological structure, coal volume, and aquifer are considered when determining the position of the west wing return air shaft of the Zhaogu No. 2 Mine and its industrial site. On the basis of various factors, this study proposes three kinds of West Wing wind wells and their industrial site layout schemes, and determines the optimal plan through technical and economic analysis of the scheme.
1 Mine Overview
Zhaogu No. 2 Mine is affiliated to Henan Energy and Chemical Group Coking Coal Company. Jingtian is located in the eastern part of Jiaozuo Coalfield, Nanxun Taixing, Xinxiang City and Huixian City. The mine was put into operation in April 2011 and was developed by vertical shaft panel. The main mining No. 1 coal seam is a single near-horizontal coal seam, which has the risk of coal and gas outburst, and the inclination angle is less than 6°, within the mine field.
The performance is characterized by high east and low west, the thickness of coal seam is 4.73~6.77m, the average is 6.12m, no heat damage and stable, and the coal dust is non-explosive. 1 is mainly composed of two seam roof sandy shale and duty sandstone, thickness of 11m, located in Upper Taiyuan coal floor limestone mine safety is threatened Mining aqueous layer, wherein the top layer slate bottom seam shown in Figure 1. From the level of the 740m level of the 2nd coal seam floor to the western boundary of the minefield, it is divided into the west wing panel, with an area of ​​about 13.2km2, and about 20 working faces can be arranged.
2 Factors affecting the location selection of wind shafts and their industrial sites
(1) The scope of service for the new return air shaft. According to the development and deployment that has been implemented, the main, auxiliary and return air shafts have been set up in the shallow depth of the coal seam in the northeastern part of the minefield. After the bottom of the wellbore, the construction of the south gate is about 900m long, and the rearward F17-1 fault strikes. Nearly EW is deployed to the three coal mines to develop the coal seams. The initial roadway is closed to the west at -626m level, while the most western coal seam in the minefield is about 1000m deep and 5.7km long. From the perspective of resource occurrence conditions, the newly added return air shaft should serve the entire west wing panel of the mine field. From the perspective of service scope and ventilation conditions, the newly added return air shaft should be arranged close to the west of the mine field (that is, the area with a large depth of coal seam).
(2) The thickness of the alluvium layer. The thickness of the third and fourth alluvial layers exposed by the borehole in the mine field is 427.30~946.37m, with an average of 666.25m, and gradually thickens from north to south and from east to west. At present, the wellbore completed by the freezing method in China has the auxiliary wellbore of Dingji Coal Mine. The alluvial layer is 525.3m thick and the freezing depth is 557m. The auxiliary wellbore of Longgu Coal Mine has an alluvial thickness of 567.7m and a freezing depth of 650m. The Wanfu Mine alluvium The thickness is about 760m [4]. Therefore, on the basis of meeting the requirements of underground development and ventilation, the wellbore should be passed through the thinner third and quaternary alluvial covering layers as much as possible.

(3) Geological structure. The fault structure in the mine field is relatively developed, and most of the fault structures are connected to the Ordovician limestone karst fissure water. Therefore, the wellbore should avoid the fault structure as much as possible and leave a certain safe distance, and make the roadway or stone gate as few as possible. Pass through or not through large faults to facilitate the construction and maintenance of the roadway.
(4) Reduce coal pressure. Due to the thick cover layer and the large coal pressure range in the wellbore and industrial sites, the wellbore should be placed in the industrial site to protect the coal pillars and the fault coal pillars or other coal pillars in the industrial area to reduce the coal loss and increase the recoverable coal. Reserves.
(5) Water content of the floor rock formation. The aquifer rock layer of the 2nd coal seam is mainly composed of L9, L8, L7, L2 limestone and Ordovician limestone. The L8 limestone of the upper aquifer of Taiyuan Formation has the best development, and the thickness of L8 aquifer is 6.77~14.78m. The thickness of the L9 limestone is 0.7~2.58m, and the two-layer limestone karst fissure is relatively developed, which is a medium aquifer with moderate water content.
The aquifer is 9.10~16.22m away from the two coal seams, and is the main water-filled aquifer of the second coal seam floor. L2 limestone develops well, gradually thickens from west to east, with a thickness of 10.01~14.68m, which is a water-rich aquifer with an upper aquifer of 85.58~104.57m from the 1st coal seam. Under normal conditions, No. 2 coal seam mining has no effect. The Ordovician limestone layer is 109.12~126.03m away from the 21st coal seam. Under normal circumstances, it does not affect the mining of the 2nd coal seam. The fracture communication has a greater threat to the mine. According to the actual situation of the Jiaozuo mining area and the actual production experience of the mine, the critical water inrush coefficient can be significantly reduced after the bottom plate is strengthened by the grouting process. Therefore, due to the rich water content of the coal-floor stratum, it is advisable to arrange the bottom-hole yard and the diversion chamber in the roof rock layer of the coal seam.
(6) Roof lithology. The pseudo-tops of the 2nd coal seam are mostly mudstones and carbonaceous mudstones with a thickness of about 0.5m, and the areas are only scattered. The thickness of the direct roof is 1~6.5m, which is dominated by sandy mudstone roof. It is a medium-hard rock type with good stability. The old top is mostly coarse, medium and fine grain sandstone (large sandstone) with a thickness of 0.94 to 19.85m and an average of 7.46m. The rock is hard and has good stability. Therefore, in areas with large sandstone thickness, it is advisable to arrange the Ma Taumen and the bottom hole yard.
3 comparison plan analysis
3.1 layout plan
(1) Option I. In order to facilitate the ventilation and transportation of the west wing panel, the wellbore and industrial site are arranged as close as possible to the middle of the west wing panel. The terrain in the area is flat, which is conducive to the layout of industrial sites. After the wellbore bottoms, the return windshield is constructed in the southeast direction and connected to the main roadway. On this basis, the panel is opened up.
(2) Option II. In order to keep the wellbore away from the fault structure and reduce the risk of wellbore construction, the wellbore and industrial site are arranged as close as possible to the middle of the service area. The wellbore falls to the south side of the main road and is connected to the main roadway through the circular yard.
(3) Option III. The wellbore is located about 100m south of the F17-1 fault, and is located in a relatively thin area of ​​the third and fourth alluvial layers, with a thickness of about 650m, which is conducive to wellbore construction. After the wellbore falls to the bottom, a returnstone door is constructed in the southeast direction to connect with the main roadway.
3.2 Technical and economic comparison analysis
The technical and economic parameters of Schemes I, II and III are compared in Table 1. Compared with the schemes I and II, the advantages are basically the same from the aspects of ventilation, auxiliary transportation and drainage in the early and late stages. The main difference is the coal volume and the distance between the wellbore and the F17-1 fault. The amount of coal in Scheme I is relatively small, but according to the three-dimensional exploration data, the wellbore may be closer to the F17-1 fault; the advantage of Scheme II is that the distance between the wellbore and the F17-1 fault is larger, which is less than the savings of the scheme I. It is a large amount of coal, and there is a cemetery at the industrial site. The land acquisition is difficult, so the three-dimensional exploration work has not yet been carried out in the area.

Comparing Schemes I and III, it can be seen that: 1 The new wellbore of Scheme I is about 3000m away from the west wing of the minefield, basically located in the middle of the west wing mining area, and the position is moderate, which can serve the entire west wing panel; the location of the scheme III wellbore is 4000m away from the west wing boundary of the minefield. Above, the ventilation negative pressure is large, it is difficult to serve the entire west wing panel; 2 the scheme I industrial site coal is located outside the existing three-dimensional exploration range, and the initial mining face coal seam is not pressed, which is beneficial to alleviate the current resource replacement of the mine. The current situation; 3 scheme I wind tunnel has a large sandstone thickness of about 10m at the bottom of the wellbore, which is conducive to the layout of the roadway; the large sandstone at the bottom of the wellbore of the scheme III is only about 5m thick, which is relatively thin, which is not conducive to the bottom of the well. Laneway layout; 4 scheme I The third and fourth alluvial layers are about 800m thick, and the wellbore freezing construction is difficult. The scheme III is all about 650m thick, and the wellbore construction is relatively easy. 5 Scheme I is due to the large thickness of the topsoil and the amount of coal Larger, except for the fault and the coal pillar of the main road, the coal pressure is about 7.15Mt, and the coal pressure of the scheme III is 5.50Mt; 6 according to the F17-1 fault orientation interpreted by the three-dimensional exploration results, it is inferred that the I wellbore is from the fault. Recently, there is a certain risk; the F17-1 fault on the north side of the scheme III wellbore is controlled by three-dimensional seismic exploration. The geological structure and coal seam occurrence are well understood. The safety rock pillar between the wellbore and the F17-1 fault is easy to guarantee, and the wellbore construction is easy. The risk is relatively small; 7 due to the deep wellbore, the construction period of the scheme I is 35.2 months, 7.2 months more than the scheme III; 8 because the wellbore arrangement in the scheme I is closer to the deep west wing of the minefield, comparable investment A little more than option III.
In summary, this study chose option I (Figure 2). The countermeasures for the shortcomings of Scheme I are as follows: 1 For the problem of large thickness of the third and Quaternary alluvial layers (about 800 m), the success of the Wanzhou Mine of Yanzhou Coal Mine through the third and Quaternary thick 760 m alluvium can be learned. Experience (incorporate layered frozen well sinking uses information construction technology, selects double-layer cast-in-place high-strength reinforced concrete composite shaft wall, and focuses on engineering information monitoring such as outer wall concrete strain to ensure construction safety and engineering quality) Solution; 2 supplement the 3D seismic exploration in the area where the scheme I is located, which can effectively control the coal seam and faults and ensure the safety of the mine construction; 3 the coal pressure of the scheme I reaches 7.15 Mt, and the later stage can be
It is solved by industrial site protection coal pillar recovery technology; 4 compared with scheme III, although the construction period of scheme I is 7.2 months and the investment is slightly more, the scheme can solve the mining problem of the whole west wing of the mine. III. In the later stage, the wellbore needs to be added to solve the mining problem of the west wing panel. The investment is greatly improved compared with the scheme I. In addition, the land acquisition and construction work must be completed. The long construction period will inevitably affect the normal production connection in the later stage of the mine.

4 Conclusion

According to the specific geological conditions of the Zhaogu No. 2 Minefield, three types of wellbore and their industrial site layout schemes were proposed, and the scheme comparison was carried out. It is considered that the wellbore and its industrial site are arranged as close as possible to the middle of the west wing panel of the mine.

references
[1] Tian Wei, Hu Jinsong, Zhou Ying. Analysis on the location selection of Chensilou mine shaft [J]. Zhongzhou Coal, 1994 (4): 21-23.
[2] Liu Jun. Research status and development trend of coal seam gas development well location technology in mining area [J]. Coal Mine Safety, 2013, 24(1): 60-63.
[3] Yang Ping, Yuan Zhaoxia. Gaohe mine industrial site location selection [J]. Coal Engineering, 2005 (2): 17-18.
[4] Chen Changyu. Discussion on the sinking method of 800m deep alluvium in Wanfu Mine [J]. Well Construction Technology, 2006, 27(5): 33-35.

Article source: "Modern Mining", 2017.3
Author: Ming Shi Fang; Henan Energy and Chemical Group Coal Company Copyright:

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