Study on Safety Tunneling Technology of Secondary Outburst Elimination by CO₂ Gas Fracturing in High-Outburst Coal Seam

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

In this manuscript, the authors studied the safety tunneling technology of secondary outburst elimination by CO2 gas fracturing in high outburst coal seam. This topic is interesting and worth of studying, the results of manuscript are also impressive. it is recommended that the authors make a minor revision, as shown in the following comments.

1. Title is fine giving the clear message what it is about.

2. The language should be carefully revised.

3. Physical quantity lacks corresponding units in the paper, such as, gas emission velocity ΔP .

4. The article describes: "According to the “Code for Prevention of Coal and Gas Outbursts” (32), the No. 3 coal seam is 129 considered to possess the risk of coal and gas outbursts". But it is not clear which standard is specific, please describe it in the text.

5. The writing of physical quantity is not standardized

6. Please carefully check Fig.10, there are several mistakes in image annotation.

7. Please clearly explain how your research provide helpful reference for the field tests.

Comments on the Quality of English Language

In this manuscript, the authors studied the safety tunneling technology of secondary outburst elimination by CO2 gas fracturing in high outburst coal seam. This topic is interesting and worth of studying, the results of manuscript are also impressive. it is recommended that the authors make a minor revision, as shown in the following comments.

1. Title is fine giving the clear message what it is about.

2. The language should be carefully revised.

3. Physical quantity lacks corresponding units in the paper, such as, gas emission velocity ΔP .

4. The article describes: "According to the “Code for Prevention of Coal and Gas Outbursts” (32), the No. 3 coal seam is 129 considered to possess the risk of coal and gas outbursts". But it is not clear which standard is specific, please describe it in the text.

5. The writing of physical quantity is not standardized

6. Please carefully check Fig.10, there are several mistakes in image annotation.

7. Please clearly explain how your research provide helpful reference for the field tests.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The article contains original research and industrial analyses on prevention, primarily reducing the risk of outburst of gas. The obtained characteristics before and after CO2 fracturing are interesting both scientifically and technologically and indicate the usefulness of the research. Below are a few minor comments and suggestions:
1. In the introduction, information on numerical modeling for the assessment of outburst of gas should be expanded;
2. In the subsection 2.1, please write what the value of vertical and horizontal stresses is;
3. In the subsection 3.2.1, please write more clearly on what basis the double-hole CO2-frac was placed, whether any calculation formulas or mining practice were used;
4. In the subsection 4.1, please add a few sentences regarding the permissible value of outburst of gas according to the standard or recommendations - so that the results constitute a form of discussion;
5. The conclusions cover the scope of the analyses and are sufficient.

Author Response

Please see the attachment

Author Response File: Author Response.pdf