Acoustic-Gas Coupling Response Law in the Whole Process of Coal and Gas Outburst

Round 1

Reviewer 1 Report

The topic of the paper fits in nicely with the Special Issue "Coal and Rock Dynamic Disaster Monitor and Prevention". As we know, coal and gas outburst is a serious safety accident that may occur in coal mine production. This paper carried out a coal and gas outburst experiment using self-developed experimental equipment and studied the coupling response law of gas pressure and acoustic emission throughout the entire outburst process. The research results have important guidance for monitoring coal and gas outburst disasters. Therefore, I suggest the manuscript can be accepted while some minor issues still need to be improved as follows.

1) How to determine the key parameters during the coal and gas outburst experiment in Table 1?

2) What is the criterion for determining the initial loading stress in Fig 4, time or gas pressure? Why chose it?

3) What is the reason for dividing the entire process of coal and gas outburst into three stages in this paper, namely the preparation stage, the gestation stage, and the development stage?

4) The evolution of AE cumulative count and cumulative energy with time during the outburst development stage was fitted by a parabolic equation. What are the fitting results of the other two stages?

5) What is the specific guiding value of research results for monitoring coal and gas outbursts?

The overall language is good. Minor editing of the English language is required.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

1. In the abstract, focus more on the research findings and summarize the initial parts of the abstract.

2. “AE” is not defined for the reader in the abstract. It is better not to use abbreviations in the abstract.

3. In the literature review, only the articles of Chinese researchers have been discussed. Hasn't research been done in other parts of the world? If there is, the introduction section should be improved by adding these studies, and if it is not, the reason should be mentioned in the introduction.

4. According to the scope of the journal (Section: Hazards and Sustainability), it is necessary to mention in the paper what is the relationship between the conducted studies and sustainability.

5. The number of tests, the conditions of each of them, and the reason for each test should be presented in Table 1.

6. Line 144 refers to Figure 3, not Figure 4.

7. In section 3, only the process of changes in the results is mentioned and scientific analysis for the reason of these changes is not provided.

8. The way of writing the conclusion section should be modified. Only the research findings should be expressed with numbering.

9. Show parabolic equations in Figure 7.

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

In this paper the evolution of gas pressure and acoustic emission during the entire process of outburst is studied, and the acoustic-gas coupling response laws of the three stages of outburst is obtained. The acoustic emission was fitted by a parabolic equation that can quantitatively characterize the coal seam stage in the outburst development stage. Overall, this study provides new ideas for monitoring coal and gas outburst disaster and improves monitoring methods, but there are still some problems that need attention before its acceptance.

1. Line 122 “CO2 was used for the coal and gas outburst test”, why CH4 was not used?

2. Line 124 “The stress concentration factor was 1.5”, Why is the stress concentration factor set to 1.5?

3. Line 245 “four processes with significant fluctuations were selected for segmented analysis”, why choose these four phases？

4. In Fig 6(a), there is a time delay of the gas pressure changes after opening the outburst door, what is the reason?

6. The paper compared the various parameters of acoustic emission in the outburst development stage with the outburst preparation stage and the outburst gestation stage. Why not compare the outburst preparation stage with the outburst gestation stage?

Author Response

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Author Response File: Author Response.docx

Reviewer 4 Report

The background and literature review is good and establishes good precedent and need for the experiment.

You use several terms throughout the paper that are unclear and detract from the content of the paper. The first is 'self-developed' and the second is 'outburst mouth'. I suspect that this may be a translation issue. 

You say that you prepared the coal sample from coal powder. Would I be correct in assuming that this is not from intact coal? The limitations of this approach need to be discussed, as compared to the use of cored samples. Justifying and explaining this choice would significantly improve the quality and relevance of the paper.

Your conclusions are more of a summary. Are you able to draw any conclusions as to how your findings may impact an in-mine outburst scenario?  

Needs some revision.  

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The authors responded to all the comments from my previous review.

Reviewer 4 Report

Response to initial issues is acceptable. 

There are still some minor issues related to the use of articles like 'a' and 'the'. These are minor, and I feel that the paper is very readable even if the English isn't completely perfect.