Experimental Study on the Mechanical Properties of Tectonic Coal Using Reconstituted Coal Specimens
Round 1
Reviewer 1 Report
Dear authors
My remarks in the PDF file
Comments for author File: 
Comments.pdf
Author Response
Reviewer #1:
The paper studies experimentally the mechanical properties of tectonic coal using reconstituted coal specimens. The study is detailed, and the conclusions describe well the main findings of the research. The abstract is clear and focuses on the main points of the study. My main remarks for correction/improvement are the following:
RESPONSE: Thanks very much for your comments. Your comments are rather valuable for improving our paper. According to your comments, we have revised our manuscript carefully. Thank you again.
(1) Page 2: and 1 mD, respectively, which are obviously lower than those of the tectonic coal in the field. But in the next line you write As far as we know and 0.01~0.001 mD. That means that the permeability of reconstituted coal of previous studies was higher than the actual. Please correct.
RESPONSE: Thanks very much for this comment. As you pointed out, the permeability of reconstituted coal samples in previous studies was significantly higher than that of the tectonic coal in the field. Therefore, those coal samples are of low compaction degree; and thus the current measurement results on the mechanical properties of tectonic coal is questionable. Given this, a new high-pressure-resistant mold was developed and a heavy press was adopted to prepare highly compacted reconstituted coal specimens in our study. Based on these highly compacted coal specimens, the mechanical properties of tectonic coal and intact coal were measured and comprehensively compared and analyzed. So, there is no problem here.
(2) Symbols VL, PL before Table 1. The L shall be subscript.
RESPONSE: Thanks very much for this comment. This comment is rather important, and we are sorry for this mistake. In the revised manuscript, we have made corresponding modification. Please see the revised manuscript.
(3) The axes titles in Figure 9 are missing.
RESPONSE: Thanks very much for this comment. This comment is rather important, and we are sorry for this mistake. In the revised manuscript, the axe title has been added. Please see the revised manuscript.
Reviewer 2 Report
The article as it is presented is centered on itself. It is a collection of results, however interesting, but is not highlighted in a sufficiently interesting way for specialists. It would therefore be necessary to compare the manufacturing principle and the innovations of the process with its results, with similar results available in the bibliography. It must be clearly shown what the article reports as advances in research. Appropriate conclusion should be withdrawn with clear guidelines for future research.
Author Response
The article as it is presented is centered on itself. It is a collection of results, however interesting, but is not highlighted in a sufficiently interesting way for specialists. It would therefore be necessary to compare the manufacturing principle and the innovations of the process with its results, with similar results available in the bibliography. It must be clearly shown what the article reports as advances in research. Appropriate conclusion should be withdrawn with clear guidelines for future research.
RESPONSE: Thanks very much for this comment. This comment is rather important. According to your comment, the innovations of our paper have been further summarized in the revised manuscript: 1) a new high-pressure-resistant mold was developed and a heavy press was adopted to prepare highly compacted reconstituted coal specimens based on the density and permeability indexes; 2) the basic mechanical properties of tectonic coal and intact coal were measured and comprehensively compared and analyzed. According to your comment, the Introduction and Conclusion of this work have been carefully modified. Please see the revised manuscript.
Reviewer 3 Report
The article presented leaves me perplexed. indeed, he deals with the use of coal in a magazine "sustainability". Coal is a non-renewable fossil material. I don't see the point of developing research on its use.
I don't see any elements of sustainable development in the paper, we just want to try to recover even more coal in dangerous areas. The paper does not show what they will be used for. No information on the social or economic context.
In view of climate change, research should be directed to combat the release of CO2.
Author Response
The article presented leaves me perplexed. indeed, he deals with the use of coal in a magazine "sustainability". Coal is a non-renewable fossil material. I don't see the point of developing research on its use. I don't see any elements of sustainable development in the paper, we just want to try to recover even more coal in dangerous areas. The paper does not show what they will be used for. No information on the social or economic context. In view of climate change, research should be directed to combat the release of CO2.
RESPONSE: Thanks very much for this comment. This comment is rather important. As you pointed out, coal is a non-renewable fossil material. However, coal cannot be completely replaced by other energy sources in the foreseeable future. Meanwhile, coalbed gas is a typical greenhouse gas. In China, approximately 20% of the coalbed gas is stored in the tectonic coal reservoir with a low permeability. Therefore, its gas extraction is rather difficult, and a large amount of coalbed gas is expected to be released into the atmosphere during the mining process. To enhance gas extraction in the tectonic reservoir and thus to reduce the greenhouse gas emissions, mechanical related permeability-improving technologies such as protective layer mining, hydraulic flushing and hydraulic slotting have been widely adopted in China. If we want to achieve efficient application of these mechanical related permeability-improving technologies, it is very necessary to master the mechanical properties of tectonic coal. In a word, the research in our paper is helpful to enhance gas extraction in the tectonic coal reservoir and to reduce the emission of greenhouse gases. Therefore, the research of this paper is closely related to sustainable development. In the revised manuscript, we have made corresponding modifications in the Introduction section. Please see the revised manuscript.
Meanwhile, many research papers on the mechanical properties of coal or rock mass have been published in this journal. For example:
[1] Wang T, Chang JC, Guo YJ. Study on deformation characteristics of surrounding rock of roadway with coal-rock interface. Sustainability 2023;15(6):5347.
[2] Li AR, Cui GZ, Wang P, Wang XJ, Hong ZT, Kong JG, Kan JG. Deformation and failure laws of surrounding rocks of coal roadways under high dynamic load and intelligent prediction. Sustainability 2023;15(2):1313.
[3] Wang XY, Zhang L. Experimental study on permeability evolution of deep coal considering temperature. Sustainability 2022;14(12):14923.
[4] Zhang HL, Xue YL, Li YG, Yin JD. Study on initial fracture characteristics of the main roof in fully mechanized caving mining of inclined coalbed. Sustainability 2022;14(21):13782.
[5] Liu YL, Li JT, Duan YW, Qin T, Liu ZW. Study on the influence of roadway structural morphology on the mechanical properties of weakly cemented soft rock roadways. Sustainability 2023;15(1):821.
Round 2
Reviewer 2 Report
The paper would be ok, provided that english is carefully checked up
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Reviewer 3 Report
The paper is better. I accept this new version
Author Response
Thanks very much for your comments. Your comments are rather valuable for improving our paper.
