Research on Gas Control Technology of “U+ Omni-Directional Roof to Large-Diameter High-Level Drilling Hole” at the End Mining Face of Multi-Source Goaf
Round 1
Reviewer 1 Report
This manuscript proposed a novel gas control scheme of "U+ omni-directional roof heading for large diameter high-level drilling” for solving the problem of gas overrun in the upper corner. The paper is of interest to researchers in the field of gas drainage, but it needs some work before it can be accepted for publication. Detailed comments are as follows:
1、In the situation of the project, the goaf of No.3 coal seam and the occurrence of coal seam are not described.
2、In the part of on-site detection of fracture zone height, please introduce the detection instruments used and the principle of detection work.
3、In the part of on-site detection of fracture zone height, please clarify the construction parameters of No.1 hole and No.5 hole under investigation.
4、The calculation process is not described when the fracture horizon is calculated according to the collected borehole fracture position. Please supplement it.
5、The first letter of the title in Figure 8(a) and Figure 9(a) should be capitalized. Please add a space between number and unit.
6、This paper describes the horizons that are not arranged in the high drilling site. In Table 2, does the height difference between the final drilling hole and the roof of the coal seam refer to the height difference between the final drilling hole and the roof of the drilling site or between the final drilling hole and the roof of the drilling site?
7、Under normal circumstances, the high-level drilling drainage only pumps the gas in the goaf and adjacent layers, and the high-level drilling is constructed in the direction of the goaf by the return air of the coal mining face, while the all-round drainage drilling is a 180-degree drilling in the high-level drilling field. What is its technical principle?
8、In the process of omni-directional drilling drainage, has the influence of drainage negative pressure on drainage effect been investigated? Under what negative pressure, the gas drainage effect is the best?
9、When the advancing degree of the coal mining face exceeds that of the drilling site, will it affect the back drilling? At this time, the drilling site will enter the goaf. How to solve the ventilation problem of the high drilling site and the gas management communication lane?
10、The design and construction of high-level drilling holes and the investigation of gas extraction effect are all based on XV1306 working face. However, in the final analysis of the relationship between air distribution and gas extraction, XV1307 working face is mentioned. Is it an error?
Author Response
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Reviewer 2 Report
The simulation of fracture zone in goaf is a conventional method without innovation. The gas drainage method is a bit innovative, but the results can also be expected. There is no comparative study with other gas drainage methods, which can not reflect the characteristics and advantages of this drainage method. Therefore, on the whole, the paper is not innovative.
Author Response
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Reviewer 3 Report
The authors provided a typical engineering study on coal mining. In my opinion, a minor revision is suggested.
1. It is recommended that the approximate location and orientation of the fractures be marked in each of the inspection images in Section 3 for the convenience of the reader.
2. It is recommended that the lithology of each rock formation be marked in detail in Figure 5.
3. It is recommended that the software used in modeling be briefly described from lines 135 to 138.
Author Response
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Round 2
Reviewer 2 Report
1. In 4.3, what are the criteria for dividing the caving zone and fracture zone?
2. In Figure 9 and Figure 10, can we add the abscissa and ordinate representing the distance?
3. 3.2, the 15# coal seam is 8.24m~13.49m, and the height of the fissure surface in the fissure zone 148 is 19.19~27.46m”。 Why do the test results of fracture zone and caving zone vary so widely.
4. The maximum height of the fracture zone measured is 27.46m, and the numerical simulation result is 51.63m. Is it contradictory?
5. Figure 12-15, the drawing is not standard and needs to be corrected.
Author Response
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